@misc{KukliDimriTammetal., author = {Kukli, Kaupo and Dimri, Mukesh Chandra and Tamm, Aile and Kemell, Marianna and K{\"a}{\"a}mbre, Tanel and Vehkam{\"a}ki, Marko and Puttaswamy, Manjunath and Stern, Raivo and Kuusik, Ivar and Kikas, Arvo and Tallarida, Massimo and Schmeißer, Dieter and Ritala, Mikko and Leskel{\"a}, Markku}, title = {Structural and Magnetic Studies on Iron Oxide and Iron-Magnesium Oxide Thin Films Deposited Using Ferrocene and (Dimethylaminomethyl)ferrocene Precursors}, series = {ECS Journal of Solid State Science and Technology}, volume = {2}, journal = {ECS Journal of Solid State Science and Technology}, number = {3}, issn = {2162-8769}, doi = {10.1149/2.004303jss}, pages = {N45 -- N54}, abstract = {Iron oxide and magnesium-doped iron oxide films were grown by atomic layer deposition in the temperature range of 350-500 ◦C from ferrocene, (dimethylaminomethyl)ferrocene, magnesiumβ-diketonate, and ozone. Phase composition of the films depended on the deposition temperature, as magnetite and/or maghemite tended to form instead of hematite upon lowering the temperature. Iron oxide layers were also mixed with magnesium oxide by alternate deposition of MgO and Fe2O3 which also favored the formation of magnetite or maghemite structure prior to hematite. Scanning electron microscopy implied the smoothening of the films after doping with magnesium oxide. Magnetometry was used to study the effects of temperature and doping levels on the magnetic properties of the films.}, language = {en} } @misc{PopoviciDelabieAdelmannetal., author = {Popovici, Mihaela and Delabie, Annelies and Adelmann, Christoph and Meersschaut, Johan and Franquet, Alexis and Tallarida, Massimo and Berg, Jaap van den and Richard, Olivier and Swerts, Johan and Tomida, Kazuyuki and Kim, Min-Soo and Tielens, Hilde and Bender, Hugo and Conard, Thierry and Jurczak, Malgorzata and Elshocht, Sven van and Schmeißer, Dieter}, title = {Understanding the Interface Reactions of Rutile TiO2 Grown by Atomic Layer Deposition on Oxidized Ruthenium}, series = {ECS Journal of Solid State Science and Technology}, volume = {2}, journal = {ECS Journal of Solid State Science and Technology}, number = {1}, issn = {2162-8769}, doi = {10.1149/2.035301jss}, pages = {N23 -- N27}, abstract = {The atomic layer deposition of titanium oxide TiO2 on ruthenium and oxidized ruthenium with titanium methoxide as metal precursor and H2O and O3 as oxidant was investigated by Rutherford backscattering (RBS) and time of flight secondary ion mass spectrometry (TOFSIMS). An ultra-thin layer of TiO2 deposited a priori with H2O plays the role of protection of Ru(Ox) substrates against etching by O3. Information about thin films (∼3 nm) interfacial reactions, thickness and structure was brought by Medium Energy Ion Scattering Spectroscopy (MEIS) and X-ray absorption spectroscopy (XAS) measurements. The growth enhancements observed in the first stages of the deposition depends on the pre-treatment (pre-oxidation, H2O based interlayer thickness) of the Ru substrate. Thick films (∼14 nm) were analyzed by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The as deposited TiO2 films are crystalline with rutile structure, as resulted from structural analyzes. However, the presence of small amounts of anatase was detected by soft X-ray absorption spectroscopy (XAS) and is strongly influenced by the surface pre-treatment of the Ru substrate. The electrical properties (equivalent oxide thickness and leakage current density) correlate with a different rutile/anatase ratio present in the films.}, language = {en} } @misc{TallaridaSchmeisser, author = {Tallarida, Massimo and Schmeißer, Dieter}, title = {In situALD experiments with synchrotron radiation photoelectron spectroscopy}, series = {Semiconductor Science and Technology}, volume = {27}, journal = {Semiconductor Science and Technology}, number = {7}, issn = {1361-6641}, doi = {10.1088/0268-1242/27/7/074010}, pages = {074010}, abstract = {In this contribution, we describe some features of atomic layer deposition (ALD) investigated by means of synchrotron radiation photoelemission spectroscopy (SR-PES). In particular, we show how the surface sensitivity of SR-PES combined with the in situ nature of our investigations can point out interactions between the substrate and ALD precursors. We observed changes on all substrates investigated, included Si, GaAs, Ru and their surface oxides. These interactions are extremely important during the first ALD cycles and induce modifications in the substrate, which might lead to its functionality enhancement.}, language = {en} } @misc{TallaridaAdelmannDelabieetal., author = {Tallarida, Massimo and Adelmann, Christoph and Delabie, Annelies and van Elshocht, Sven and Caymax, Matty and Schmeißer, Dieter}, title = {GaAs clean up studied with synchrotron radiation photoemission}, series = {IOP Conference Series : Materials Science and Engineering}, journal = {IOP Conference Series : Materials Science and Engineering}, number = {41}, issn = {1757-899X}, doi = {10.1088/1757-899X/41/1/012003}, pages = {012003}, abstract = {In this contribution we describe the chemical changes at the surface of GaAs upon adsorption of tri-methyl-aluminum (TMA). TMA is used to grow Al2O3 with atomic layer deposition (ALD) usually using H2O as oxygen source. Recently, it was pointed out that the adsorption of TMA on various III-V surfaces reduces the native oxide, allowing the growth of an abrupt III-V/High-K interface with reduced density of defects. Synchrotron radiation photoemission spectroscopy (SR-PES) is a powerful method to characterize surfaces and interfaces of many materials, as it is capable todetermine their chemical composition as well as the electronic properties. We performed in-situ SR-PES measurements after exposing a GaAs surface to TMA pulses at about 250°C. Upon using the possibility of tuning the incident photon energy we compared the Ga3d spectra at 41 eV, 71 eV, 91 eV and 121 eV, as well as the As3d at 71 eV and 91 eV. Finally, we show that using SR-PES allows a further understanding of the surface composition, which is usually not accessible with other techniques.}, language = {en} } @inproceedings{SchmeisserRichterTallarida, author = {Schmeißer, Dieter and Richter, Matthias and Tallarida, Massimo}, title = {Intrinsic defects in TiO2 to explain resistive switching devices}, series = {Frontiers in Electronic Materials: A Collection of Extended Abstracts of the Nature Conference Frontiers in Electronic Materials, June 17 to 20 2012, Aachen, Germany}, booktitle = {Frontiers in Electronic Materials: A Collection of Extended Abstracts of the Nature Conference Frontiers in Electronic Materials, June 17 to 20 2012, Aachen, Germany}, editor = {Heber, J{\"o}rg and Schlom, Darrell and Tokura, Yoshinori and Waser, Rainer and Wuttig, Matthias}, publisher = {Wiley-VCH}, address = {Weinheim}, isbn = {978-3-527-41191-7}, doi = {10.1002/9783527667703.ch45}, pages = {255 -- 256}, language = {en} } @misc{KukliKemellPuukilainenetal., author = {Kukli, Kaupo and Kemell, Marianna and Puukilainen, Esa and Aarik, Jaan and Aidla, Aleks and Sajavaara, Timo and Laitinen, Mikko and Tallarida, Massimo and Sundqvist, Jonas and Ritala, Mikko and Leskel{\"a}, Markku}, title = {Atomic Layer Deposition of Ruthenium Films from (Ethylcyclopentadienyl)(pyrrolyl)ruthenium and Oxygen}, series = {Journal of the Electrochemical Society}, volume = {158}, journal = {Journal of the Electrochemical Society}, number = {3}, issn = {0013-4651}, doi = {10.1149/1.3533387}, pages = {D158 -- D165}, abstract = {Ru films were grown by atomic layer deposition in the temperature range of 275-350 degrees C using (ethylcyclopentadienyl)(pyrrolyl)ruthenium and air or oxygen as precursors on HF-etched Si, SiO(2), ZrO(2), and TiN substrates. Conformal growth was examined on three-dimensional silicon substrates with 20: 1 aspect ratio. ZrO(2) promoted the nucleation of Ru most efficiently compared to other substrates, but the films roughened quickly on ZrO(2) with increasing film thickness. The minimum number of cycles required to form continuous and conductive metal layers could be decreased by increasing the length of the oxygen pulse. In order to obtain well-conducting Ru films growth to thicknesses of at least 8-10 nm on any surface was necessary. Resistivities in the ranges of 30-60 and 14-16 mu Omega . cm were achieved for 4-6 and 10-15 nm thick films, respectively. Delamination became an issue in the Ru films grown to thicknesses about 10 nm and higher.}, language = {en} } @inproceedings{Tallarida, author = {Tallarida, Massimo}, title = {III-V/oxide interfaces investigated with synchrotron radiation photoemission spectroscopy}, series = {Meeting Abstracts-Electrochemical Society, Pacific Rim Meeting on Electrochemical and Solid-State Science, Honolulu, 2012}, booktitle = {Meeting Abstracts-Electrochemical Society, Pacific Rim Meeting on Electrochemical and Solid-State Science, Honolulu, 2012}, publisher = {The Electrochemical Society}, pages = {2587 -- 2587}, language = {en} } @misc{TallaridaAdelmannDelabieetal., author = {Tallarida, Massimo and Adelmann, Christoph and Delabie, Annelies and Elshocht, Sven van and Caymax, Matty and Schmeißer, Dieter}, title = {III-V/Oxide Interfaces Investigated with Synchrotron Radiation Photoemission Spectroscopy}, series = {ECS Transactions}, volume = {50}, journal = {ECS Transactions}, number = {4}, issn = {1938-6737}, doi = {10.1149/05004.0123ecst}, pages = {123 -- 128}, abstract = {We used synchrotron radiation photoemission spectroscopy (SR-PES) to investigate the surface of GaAs and other III-V semiconductors after tri-methyl-aluminum (TMA) pulses performed at 250{degree sign}C. We observed the removal of native oxide and the growth of Al-oxide upon measuring the As3d, Ga3d, Al2p and VB spectra. After seven TMA pulses we performed one water pulse. As3d and Ga3d peaks showed almost no lineshape change, but a decrease of intensity due to the water adsorption. The valence band shows a change in the secondary electron cut-off and the decrease of work function. We conclude that water mostly adsorbs molecularly and induces the work function decrease. The molecular absorption of water indicates that the seven TMA pulses produce a passivated surface only partially terminated with OH groups.}, language = {en} } @misc{BarrecaCarraroGasparottoetal., author = {Barreca, Davide and Carraro, Giorgio and Gasparotto, Alberto and Maccato, Chiara and Rossi, Francesca and Salviati, Giancarlo and Tallarida, Massimo and Das, Chittaranjan and Fresno, Fernando and Korte, Dorota and Štangar, Urška Lavrenčič and Franko, Mladen and Schmeißer, Dieter}, title = {Surface Functionalization of Nanostructured Fe2O3 Polymorphs: From Design to Light-Activated Applications}, series = {ACS Applied Materials \& Interfaces}, volume = {5}, journal = {ACS Applied Materials \& Interfaces}, number = {15}, issn = {1944-8252}, doi = {10.1021/am401475g}, pages = {7130 -- 7138}, abstract = {Nanostructured iron(III) oxide deposits are grown by chemical vapor deposition (CVD) at 400-500 °C on Si(100) substrates from Fe(hfa)2TMEDA (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA = N,N,N′N′-tetramethylethylenediamine), yielding the selective formation of α-Fe2O3or the scarcely studiedε-Fe2O3 polymorphs under suitably optimized preparative conditions. By using Ti(OPr i)4(OPri= iso-propoxy) and water asatomic layer deposition (ALD) precursors, we subsequently functionalized the obtained materials at moderate temperatures (<300°C) by an ultrathin titanomagnetite (Fe3-xTixO4) overlayer. An extensive multitechnique character-ization, aimed at elucidating the system structure, morphology, composition and optical properties, evidenced that the photoactivated hydrophilic and photocatalytic behavior of the synthesized materials is dependent both on iron oxide phase composition and ALD surface modification. The proposed CVD/ALD hybrid synthetic approach candidates itself as a powerful tool for a variety of applications where semiconductor-based nanoarchitectures can benefit from the coupling with an ad hoc surface layer.}, language = {en} } @misc{AdelmannCuypersTallaridaetal., author = {Adelmann, Christoph and Cuypers, Daniel and Tallarida, Massimo and Rodriguez, Leonard and De Clercq, Astrid and Friedrich, Daniel and Conard, Thierry and Delabie, Annelies and Seo, Jin Won and Locquet, Jean-Pierre and De Gendt, Stefan and Schmeißer, Dieter and Elshocht, Sven van and Caymax, Matty}, title = {Surface Chemistry and Interface Formation during the Atomic Layer Deposition of Alumina from Trimethylaluminum and Water on Indium Phosphide}, series = {Chemistry of Materials}, volume = {25}, journal = {Chemistry of Materials}, number = {7}, issn = {1520-5002}, doi = {10.1021/cm304070h}, pages = {1078 -- 1091}, abstract = {The surface chemistry and the interface formation during the initial stages of the atomic layer deposition (ALD) of Al2O3 from trimethylaluminum (TMA) and H2O on InP(100)were studied by synchrotron radiation photoemission spectroscopy and scanning tunneling microscopy. The effect of the ex situ surface cleaning by either H2SO4 or (NH4)2S was examined. It is shown that the native oxide on the InP surface consisted mainly of indium hydrogen phosphates with a P enrichment at the interface with InP. After a (NH4)2S treatment, S was present on the surface as a sulfide in both surface and subsurface sites. Exposure to TMA led to the formation of a thin AlPO4 layer, irrespective of the surface cleaning. The surface Fermi level of p-type InP was found to be pinned close to midgap after H2SO4 cleaning and moved only slightly further toward the conduction band edge upon TMA exposure, indicating that the AlPO4/InP interface was rather defective. (NH4)2S passivation led to a Fermi level position of p-type InP close to the conduction band edge. Hence, the InP surface was weakly inverted, which can be attributed to surface doping by S donors. TMA exposure was found to remove surface S, which was accompanied by a shift of the Fermi level to midgap, consistent with the removal of (part of) the S donors in combination with a defective AlPO4/InP interface. Further TMA/H2O ALD did not lead to any detectable changes of the AlPO4/InP interface and suggested simple overgrowth with Al2O3.}, language = {en} } @misc{RossiFabbriTallaridaetal., author = {Rossi, Francesca and Fabbri, Filippo and Tallarida, Massimo and Schmeißer, Dieter and Modreanu, Mircea and Attolini, Giovanni and Salviati, Giancarlo}, title = {Structural and luminescence properties of HfO2 nanocrystals grown by atomic layer deposition on SiC/SiO2 core/shell nanowires}, series = {Scripta Materialia}, volume = {69}, journal = {Scripta Materialia}, number = {10}, issn = {1359-6462}, doi = {10.1016/j.scriptamat.2013.08.017}, pages = {744 -- 747}, abstract = {In this work we report the morphological, structural and luminescence properties of HfO2 nanocrystals grown on the surface of SiC/SiO2 core/shell nanowires by atomic layer deposition. All the studies are carried out in comparison with HfO2 nanocrystal aggregates grown on planar oxidized silicon substrates. The structural analyses reveal that HfO2has monoclinic structure with dif-ferent orientations. The cathodoluminescence emission shows the main components at 2.7 and 2.3 eV, deeply influenced by the arrangement and aggregation of the nanocrystals.}, language = {en} } @misc{HaeberleHenkelGargourietal., author = {Haeberle, J{\"o}rg and Henkel, Karsten and Gargouri, Hassan and Naumann, Franziska and Gruska, Bernd and Arens, Michael and Tallarida, Massimo and Schmeißer, Dieter}, title = {Ellipsometry and XPS comparative studies of thermal and plasma enhanced atomic layer deposited Al2O3-films}, series = {Beilstein Journal of Nanotechnology}, volume = {2013}, journal = {Beilstein Journal of Nanotechnology}, number = {4}, issn = {2190-4286}, doi = {10.3762/bjnano.4.83}, pages = {732 -- 742}, abstract = {We report on results on the preparation of thin (<100 nm) aluminum oxide (Al2O3) films on silicon substrates using thermal atomic layer deposition (T-ALD) and plasma enhanced atomic layer deposition (PE-ALD) in the SENTECH SI ALD LL system. The T-ALD Al2O3layers were deposited at 200 °C, for the PE-ALD films we varied the substrate temperature range between room temperature (rt) and 200 °C. We show data from spectroscopic ellipsometry (thickness, refractive index, growth rate) over 4" wafers and correlatethem to X-ray photoelectron spectroscopy (XPS) results. The 200°C T-ALD and PE-ALD processes yield films with similar refractive indices and with oxygen to aluminum elemental ratios very close to the stoichiometric value of 1.5. However, in both also fragments of the precursor are integrated into the film. The PE-ALD films show an increased growth rate and lower carbon contaminations. Reducing the deposition temperature down to rt leads to a higher content of carbon and CH-species. We also find a decrease of the refractive index and of the oxygen to aluminum elemental ratio as well as an increase of the growth rate whereas the homogeneity of the film growth is not influenced significantly. Initial state energy shifts in all PE-ALD samples are observed which we attribute to a net negative charge within the films.}, language = {en} } @inproceedings{CuypersDorpTallaridaetal., author = {Cuypers, Daniel and Dorp, Dennis H. von and Tallarida, Massimo and Brizzi, Simone and Rodriguez, Leonard and Conard, Thierry and Arnauts, Sophia and Schmeißer, Dieter and Adelmann, Christoph and De Gendt, Stefan}, title = {Study of InP Surfaces After Wet Chemical Treatments}, series = {Meeting Abstracts-Electrochemical Society, San Francisco, 2013}, booktitle = {Meeting Abstracts-Electrochemical Society, San Francisco, 2013}, publisher = {The Electrochemical Society}, pages = {S. 2132}, language = {en} } @misc{CuypersDorpTallaridaetal., author = {Cuypers, Daniel and Dorp, Dennis H. von and Tallarida, Massimo and Brizzi, Simone and Rodriguez, Leonard and Conard, Thierry and Arnauts, Sophia and Schmeißer, Dieter and Adelmann, Christoph and De Gendt, Stefan}, title = {Study of InP Surfaces after Wet Chemical Treatments}, series = {ECS Transactions}, volume = {58}, journal = {ECS Transactions}, number = {6}, issn = {1938-6737}, doi = {10.1149/05806.0297ecst}, pages = {297 -- 303}, abstract = {In this work synchrotron radiation photoemission spectroscopy (SRPES) is used to study InP surfaces after different wet chemical treatments. All results are compared to a typical fingerprint of surface components present on an as received InP sample. It is shown that acidified (HCl and H₂SO₄) treatments efficiently remove the native phosphate, although components like Pᴼ, Inᴼ and P(2±∆)+ remain present. In alkaline solution (NH₄OH) oxide remains present at the surface. As an alternative treatment, the immersion into (NH₄)₂S was studied. This passivation treatment results in fewer surface components which suggests that a higher quality surface is obtained.}, language = {en} } @misc{CuypersDorpTallaridaetal., author = {Cuypers, Daniel and Dorp, Dennis H. von and Tallarida, Massimo and Brizzi, Simone and Conard, Thierry and Rodriguez, Leonard and Mees, M. and Arnauts, Sophia and Schmeißer, Dieter and Adelmann, Christoph and De Gendt, Stefan}, title = {Study of InP Surfaces after Wet Chemical Treatments}, series = {ECS Journal of Solid State Science and Technology}, volume = {3}, journal = {ECS Journal of Solid State Science and Technology}, number = {1}, issn = {2162-8777}, doi = {10.1149/2.005401jss}, pages = {N3016 -- N3022}, abstract = {The influence of different wet chemical treatments (HCl, H₂SO₄, NH₄OH) on the composition of InP surfaces is studied by using synchrotron radiation photoemission spectroscopy (SRPES). It is shown that a significant amount of oxide remains present after immersion in a NH₄OH solution which is ascribed to the insolubility of In³⁺ at higher pH values. Acidic treatments efficiently remove the native oxide, although components like Pᴼ, Inᴼ and P(2±Δ)+ suboxides are observed. Alternatively, the influence of a passivation step in (NH₄)₂S solution on the surface composition was investigated. The InP surface after immersion into (NH₄)₂S results in fewer surface components, without detection of Pᴼ and P(2±Δ)+ suboxides. Finally, slight etching of InP surfaces in HCl/H₂O₂ solution followed by a native oxide removal step, showed no significant effect on the surface composition.}, language = {en} } @misc{DasTallaridaSchmeisser, author = {Das, Chittaranjan and Tallarida, Massimo and Schmeißer, Dieter}, title = {Linear dichroism in ALD layers of TiO₂}, series = {Environmental Earth Sciences}, volume = {70}, journal = {Environmental Earth Sciences}, number = {8}, issn = {1866-6280}, doi = {10.1007/s12665-013-2836-7}, pages = {3785 -- 3795}, abstract = {We prepare TiO₂film by ALD and study their electronic properties by soft X-ray absorption spectroscopy (XAS) and photoelectron spectroscopy. We focus on XAS and X-ray linear dichroism to indentify band onset and learn about local distortion of the Ti-O octahedral atomic and about defects which cause Ti-based electronic states within the band gap.}, language = {en} } @misc{HenkelGargouriGruskaetal., author = {Henkel, Karsten and Gargouri, Hassan and Gruska, Bernd and Arens, Michael and Tallarida, Massimo and Schmeißer, Dieter}, title = {Capacitance and conductance versus voltage characterization of Al2O3 layers prepared by PE-ALD at 25°C ≤ T ≤ 200°C}, series = {Journal of Vacuum Science and Technology A}, volume = {1}, journal = {Journal of Vacuum Science and Technology A}, number = {32}, doi = {10.1116/1.4831897}, pages = {01A107-1 -- 01A107-10}, abstract = {In this work, plasma enhanced atomic layer deposited (PE-ALD) samples were prepared at substrate temperatures in the range between room temperature (RT) and 200 °C and investigated by capacitance-voltage and conductance-voltage recordings. The measurements are compared to standard thermal atomic layer deposition (T-ALD) at 200 °C. Very low interface state density (D it) ~1011 eV-1 cm-2 could be achieved for the PE-ALD process at 200 °C substrate temperature after postdeposition anneal (PDA) in forming gas at 450 °C. The PDA works very effectively for both the PE-ALD and T-ALD at 200 °C substrate temperature delivering also similar values of negative fixed charge density (N fix) around -2.5 × 1012 cm-2. At the substrate temperature of 150 °C, highest N fix (-2.9 × 1012 cm-2) and moderate D it (2.7 × 1011 eV-1 cm-2) values were observed. The as deposited PE-ALD layer at RT shows both low D it in the range of (1 to 3) × 1011 eV-1 cm-2 and low N fix (-4.4 × 1011 cm-2) at the same time. The dependencies of N fix, D it, and relative permittivity on the substrate temperatures and its adjustability are discussed.}, language = {en} } @misc{TallaridaDasSchmeisser, author = {Tallarida, Massimo and Das, Chittaranjan and Schmeißer, Dieter}, title = {Quantum size effects in TiO2 thin films grown by atomic layer deposition}, series = {Beilstein Journal of Nanotechnology}, journal = {Beilstein Journal of Nanotechnology}, number = {5}, issn = {2190-4286}, doi = {10.3762/bjnano.5.7}, pages = {77 -- 82}, abstract = {We study the atomic layer deposition of TiO2 by means of X-ray absorption spectroscopy. The Ti precursor, titanium isopropoxide, was used in combination with H2O on Si/SiO2 substrates that were heated at 200 °C. The low growth rate (0.15 {\AA}/cycle) and the in situ characterization permitted to follow changes in the electronic structure of TiO2 in the sub-nanometer range, which are influenced by quantum size effects. The modified electronic properties may play an important role in charge carrier transport and separation, and increase the efficiency of energy conversion systems.}, language = {en} } @misc{AdelmannSchramChewetal., author = {Adelmann, Christoph and Schram, Tom and Chew, Soon Aik and Woicik, J. C. and Brizzi, Simone and Tallarida, Massimo and Schmeißer, Dieter and Horiguchi, Naoto and Elshocht, Sven van and Ragnarsson, Lars-{\AA}ke}, title = {On the scalability of doped hafnia thin films}, series = {Applied Physics Letters}, journal = {Applied Physics Letters}, number = {104}, issn = {0003-6951}, doi = {10.1063/1.4870075}, pages = {122906-1 -- 122906-4}, abstract = {The scaling behavior of Gd- and Al-doped HfO2 films as gate dielectrics in metal-oxide-semiconductor (MOS) capacitors was studied. For equivalent oxide thicknesses (EOTs) in the range of 10 {\AA}, crystallized Gd:HfO2 showed higher leakage current densities than crystallized Al:HfO2, with undoped HfO2 in between. Ultimately, the scalability of Al:HfO2 was limited by the ability to crystallize the films at a given thermal budget. As a result, for post-deposition annealing at 800 °C, the EOT of Al:HfO2 based MOS capacitors was limited to ∼8 {\AA}. However, for such an EOT, leakage current densities were reduced by about 100× with respect to HfO2. This demonstrates the high potential of Al:HfO2 for low-standby-power MOS devices.}, language = {en} } @inproceedings{HenkelTallaridaHaeberleetal., author = {Henkel, Karsten and Tallarida, Massimo and Haeberle, J{\"o}rg and Gargouri, Hassan and Naumann, Franziska and Gruska, Bernd and Arens, Michael and Schmeißer, Dieter}, title = {PE-ALD-Al2O3-Schichten f{\"u}r die Passivierung von Solarzellen}, series = {Tagungsband Photovoltaik-Meeting: Anwendungen-Qualit{\"a}t-Perspektiven, Senftenberg, 16.04.2014}, booktitle = {Tagungsband Photovoltaik-Meeting: Anwendungen-Qualit{\"a}t-Perspektiven, Senftenberg, 16.04.2014}, editor = {Gl{\"u}ck, Bernhard K. and Schmidt, Sindy and Stein, Erhard and Raschke, J{\"o}rg-Uwe and Richter, Hans}, publisher = {Cottbus-Senftenberg}, address = {BTU}, pages = {7 -- 14}, abstract = {D{\"u}nne Al2O3-Schichten wurden bei Substrattemperaturen zwischen Raumtemperatur und 200°C mittels PE-ALD auf Si-Substraten abgeschieden und ellipsometrisch, spektroskopisch und elektrisch charakterisiert. Ihr Potenzial f{\"u}r die chemische und Feldeffektpassivierung der Oberfl{\"a}chenrekombination wird bewertet.}, language = {de} } @misc{TallaridaDasCibrevetal., author = {Tallarida, Massimo and Das, Chittaranjan and Cibrev, Dejan and Kukli, Kaupo and Tamm, Aile and Ritala, Mikko and Lana-Villarreal, Teresa and Gómez, Roberto and Leskel{\"a}, Markku and Schmeißer, Dieter}, title = {Modification of Hematite Electronic Properties with Trimethyl Aluminum to Enhance the Efficiency of Photoelectrodes}, series = {The Journal of Physical Chemistry Letters}, volume = {5}, journal = {The Journal of Physical Chemistry Letters}, number = {20}, doi = {10.1021/jz501751w}, pages = {3582 -- 3587}, abstract = {The electronic properties of hematite were investigated by means of synchrotron radiation photoemission (SR-PES) and X-ray absorption spectroscopy (XAS). Hematite samples were exposed to trimethyl aluminum (TMA) pulses, a widely used Al-precursor for the atomic layer deposition (ALD) of Al2O3. SR-PES and XAS showed that the electronic properties of hematite were modified by the interaction with TMA. In particular, the hybridization of O 2p states with Fe 3d and Fe 4s4p changed upon TMA pulses due to electron inclusion as polarons. The change of hybridization correlates with an enhancement of the photocurrent density due to water oxidation for the hematite electrodes. Such an enhancement has been associated with an improvement in charge carrier transport. Our findings open new perspectives for the understanding and utilization of electrode modifications by very thin ALD films and show that the interactions between metal precursors and substrates seem to be important factors in defining their electronic and photoelectrocatalytic properties.}, language = {en} } @misc{IndraMenezesSahraieetal., author = {Indra, Arindam and Menezes, Prashanth W. and Sahraie, Nastaran Ranjbar and Bergmann, Arno and Das, Chittaranjan and Tallarida, Massimo and Schmeißer, Dieter and Strasser, Peter and Driess, Matthias}, title = {Unification of Catalytic Water Oxidation and Oxygen Reduction Reactions: Amorphous Beat Crystalline Cobalt Iron Oxides}, series = {Journal of the American Chemical Society}, volume = {2014}, journal = {Journal of the American Chemical Society}, number = {136}, issn = {1520-5126}, doi = {10.1021/ja509348t}, pages = {17530 -- 17536}, abstract = {Catalytic water splitting to hydrogen and oxygen is considered as one of the convenient routes for the sustainable energy conversion. Bifunctional catalysts for the electrocatalytic oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) are pivotal for the energy conversion and storage, and alternatively, the photochemical water oxidation in biomimetic fashion is also considered as the most useful way to convert solar energy into chemical energy. Here we present a facile solvothermal route to control the synthesis of amorphous and crystalline cobalt iron oxides by controlling the crystallinity of the materials with changing solvent and reaction time and further utilize these materials as multifunctional catalysts for the unification of photochemical and electrochemical water oxidation as well as for the oxygen reduction reaction. Notably, the amorphous cobalt iron oxide produces superior catalytic activity over the crystalline one under photochemical and electrochemical water oxidation and oxygen reduction conditions.}, language = {en} } @misc{DasHenkelTallaridaetal., author = {Das, Chittaranjan and Henkel, Karsten and Tallarida, Massimo and Schmeißer, Dieter and Gargouri, Hassan and K{\"a}rkk{\"a}nen, Irina and Schneidewind, Jessica and Gruska, Bernd and Arens, Michael}, title = {Thermal and plasma enhanced atomic layer deposition of TiO2: Comparison of spectroscopic and electric properties}, series = {Journal of Vacuum Science and Technology A}, volume = {2015}, journal = {Journal of Vacuum Science and Technology A}, number = {33}, issn = {1520-8559}, doi = {10.1116/1.4903938}, pages = {01A144-1 -- 01A144-8}, abstract = {Titanium oxide (TiO2) deposited by atomic layer deposition (ALD) is used as a protective layer in photocatalytic water splitting system as well as a dielectric in resistive memory switching. The way ALD is performed (thermally or plasma-assisted) may change the growth rate as well as the electronic properties of the deposited films. In the present work, the authors verify the influence of the ALD mode on functional parameters, by comparing the growth rate and electronic properties of TiO2 films deposited by thermal (T-) and plasma-enhanced (PE-) ALD. The authors complete the study with the electrical characterization of selected samples by means of capacitance-voltage and current-voltage measurements. In all samples, the authors found a significant presence of Ti3+ states, with the lowest content in the PE-ALD grown TiO2 films. The observation of Ti3+ states was accompanied by the presence of in-gap states above the valence band maximum. For films thinner than 10 nm, the authors found also a strong leakage current. Also in this case, the PE-ALD films showed the weakest leakage currents, showing a correlation between the presence of Ti3+ states and leakage current density.}, language = {en} } @inproceedings{TallaridaSohalSchmeisser, author = {Tallarida, Massimo and Sohal, Rakesh and Schmeißer, Dieter}, title = {Electronic properties of the 2x1 3C-SiC surface reconstruction studied with resonant photoemission}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 41}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 41}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, isbn = {0420-0195}, pages = {S. 239}, abstract = {We have studied the 2x1 reconstructed surface of the 3C-SiC polytype by means of photoemission spectroscopy. The reconstruction was characterized through Si2p and C1s core level and angle-integrated valence band spectroscopy, and confirmed by the observation of a two-domain 2x1 LEED pattern. The electronic properties of this surface were investigated by collecting valence band spectra at photon energies near the Si2p and C1s absorption edges. The results show a strong dependence of the photoemission intensity on the excitation energy with characteristic resonances for certain valence band features. With a detailed study of the resonances we are able to assign the electronic origin of the resonating states and the nature of the electronic transition near the absorption edges.}, language = {en} } @inproceedings{KolanekKaravaevTallaridaetal., author = {Kolanek, Krzysztof and Karavaev, Konstantin and Tallarida, Massimo and Schmeißer, Dieter}, title = {Atomic layer deposition of HfO2 onto SiO2 substrates investigated in-situ by non-contact UHV/AFM}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 248}, abstract = {We investigated in-situ the atomic layer deposition (ALD) of HfO2 onto SiO2 substrates with ultra high vacuum (UHV) non-contact atomic force microscope (NC-AFM). The ALD process was started after detailed analysis of the initial Si(001)/SiO2 substrate. The ALD cycles, made by using tetrakis-di-methyl-amido-Hf (TDMAHf) and water as precursors, were performed on the SiO2 substrate maintained at 230 ∘C. We studied the relation between the film growth and the root mean square surface roughness, surface skewness, kurtosis, fractal dimension and correlation length. In the initial stages of the ALD process with our analysis of the surface height histograms we were capable of determination: HfO2 layer thickness, surface coverage and surface roughness of a substrate and deposited material. Observation of the surface height histograms evolution during deposition allowed us to verify conformal and effective ALD growth on SiO2 substrate. With this detailed analysis of the surface topography we confirmed the completion of the first HfO2 layer after four ALD cycles.}, language = {en} } @inproceedings{MichlingTallaridaKolaneketal., author = {Michling, Marcel and Tallarida, Massimo and Kolanek, Krzysztof and Schmeißer, Dieter}, title = {In-situ EELS and UPS measurements on HfO2 ALD layers}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, abstract = {In this contribution we report on our in-situ cycle-by-cycle (up to 10 cycles) investigations of the HfO2 ALD process using the methods of EELS and UPS. We used TDMA-Hf as a precursor and p-type Si wafer with natural oxide as the substrate. The EELS measurements were done with a primary energy of 52,5 eV and the UPS measurements with He I (21,218 eV). The change in the onset of the loss function is readily observed. Already after two cycles the value approach to the bulk value of HfO2. Upon ALD growth there is a remarkable decrease in the intensity of states within the gap. They are rather smooth and saturate after 10 cycles. With UPS we follow the variation of the VB onset and changes in the secondary electron onset. We summarize our data in a band diagram not based on bulk values but on cycle dependent quantities. With these cycle-by-cycle experiments we study the initial growth of HfO2 especially in the very first cycles.}, language = {en} } @inproceedings{StarzykTallaridaSchmeisser, author = {Starzyk, Łukasz and Tallarida, Massimo and Schmeißer, Dieter}, title = {Electrically optimized high-κ metal gate MOSFET by specific modification of the band alignment}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 231}, abstract = {The electrical optimization of metal/oxide/semiconductor gate stacks by specific modification of the band alignment for advanced MOS technology incorporating high dielectric constant (κ) materials is explored. Because of requirements concerning continued scaling of MOSFET transistors, gate oxides and cobalt electrode have been grown successively on Si substrate respectively by means of atomic layer deposition (ALD) and evaporation. The thicknesses of high-κ films were around 2 nm. In case of work function engineering, interfaces' chemistry plays a fundamental role. We applied synchrotron radiation based x-ray photoelectron spectroscopy (SR XPS) to characterize our samples, which allows step by step in situ investigations. Co 2p, Al 2p, Hf 4f, Si 2p and O 1s core levels spectra were measured and analyzed. From valence band (VB) spectra we determined Schottky barrier height and electronic bands offsets.}, language = {en} } @inproceedings{WyrodekTallaridaSchmeisseretal., author = {Wyrodek, Jakub and Tallarida, Massimo and Schmeißer, Dieter and Weisheit, Martin}, title = {Determination of interfacial layers in high - k ALD nanolaminate materials by ARXPS and SRXPS measurements}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 232}, abstract = {The interfacial layers of high dielectric constant (high - k) nanolaminate films are here explored. Problems concerning ALD nanolaminate layers deals mainly with lack of accurate methods to determine in depth profile of few nm thick stacks. Modified angle resolved XPS(ARXPS) and synchrotron radiation XPS(SRXPS) are proposed as methods suitable in layer profiling. Studied stacks containing ZrO/HfO or AlO/ZrO, were prepared on Si substrates by atomic layer deposition (ALD). Two sets of experiments were covered. First dealt with initial growth (up to 20 cycles, with thickness d < 2nm) of AlO/ZrO and included layer by layer insitu investigation by SRXPS. Second experiment refer to industrial grown ZrO/HfO films ( d ∼ 3nm ) processed with various parameters resulting in both, layer by layer and homogenous depositions. For those samples exsitu XPS, with angle dependent variation of probing depth, measurements were covered. By comparing obtained intensity ratios for different angles with computational developed stack model it was found that no simple layer by layer but some intermixing growth occurred including interaction with silicon substrate.}, language = {en} } @inproceedings{KaravaevTallaridaSchmeisseretal., author = {Karavaev, Konstantin and Tallarida, Massimo and Schmeißer, Dieter and Zschech, Ehrenfried}, title = {In-situ ALD growth of Hafnium oxide films}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 43}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 244}, abstract = {We report on a novel system for in-situ atomic layer growth (ALD) of high-k dielectric films. First results were obtained for Hf-oxide samples by using Hf-tetrachloride as precursor and water as oxidizer. We compare the photoelectron spectra of Si2p, O1s and Hf4f of our in-situ prepared films with samples (ex-situ) prepared by industrial ALD reactors and discuss similarities and differences observed in the core level spectra of the various samples by considering the different growth conditions.}, language = {en} } @inproceedings{TallaridaKaravaevSchmeisseretal., author = {Tallarida, Massimo and Karavaev, Konstantin and Schmeißer, Dieter and Zschech, Ehrenfried}, title = {Photoemission and absorption spectroscopy for in situ investigations of the ALD growth}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 43}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 43}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 242}, abstract = {We have investigated the growth of Hf-oxide on Si by means of photoemission and X-ray absorption spectroscopy using synchrotron radiation at Bessy, Berlin. The Hf-oxide layers were grown via atomic layer deposition (ALD) using an in-situ ALD reactor attached to the investigation chamber. The XPS and XAS spectra were measured after every deposition cycle by transferring the sample into the investigation chamber without breaking the vacuum. From the experimental data we have obtained information about the early stages of the Hf-oxide growth, concerning in particular the reactivity of the interface with Si. Due to the possibility to study the layers after every cycle and with different oxidation parameters without exposing them to contaminants, the in situ investigation revealed to be a very important method to understand the growth properties of Hf-oxide.}, language = {en} } @inproceedings{KaravaevTallaridaSchmeisser, author = {Karavaev, Konstantin and Tallarida, Massimo and Schmeißer, Dieter}, title = {Evolution of the interfacial layer during the atomic layer deposition of HfO2 on Si/SiO2 substrates}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 160}, abstract = {We studied the formation of the interfacial layer in the Si/SiO2/HfO2 system using the in-situ Atomic Layer Deposition (ALD) reactor developed in our group [1,2]. We measured the X-ray photoelectron and X-ray absorption spectra with synchrotron radiation at the beamline U49-2/PGM2-BESSY II. The ALD growth was obtained using different Hf-precursors (HfCl4,TEMAHf and TDMAHf) on various prepared substrates at different temperatures. The investigation was carried out in-situ giving the possibility to determine the properties of the grown film after every ALD cycle without breaking the vacuum. We observed the evolution of the Si/SiO2/HfO2 system during the formation of first three Hf-oxide layers, detecting the interfacial growth of SiO2 during the initial ALD cycles from the XPS spectra of Si2p. We discuss how the interfacial layer growth depends on the various ALD parameters. [1] M. Tallarida, K. Karavaev, and D. Schmeisser, J. Appl. Phys. 104, 064116 (2008); [2] M. Tallarida, K. Karavaev, and D. Schmeisser, J. Vac. Sci. Technol. B, accepted for publication.}, language = {en} } @inproceedings{KolanekKaravaevTallaridaetal., author = {Kolanek, Krzysztof and Karavaev, Konstantin and Tallarida, Massimo and Schmeißer, Dieter}, title = {In-situ investigations of the atomic layer deposition of HfO2 with UHV/AFM}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 44}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 160}, abstract = {We studied in-situ the atomic layer deposition (ALD) of HfO2 with ultra high vacuum (UHV) atomic force microscope (AFM), using the ALD reactor developed by our group [1, 2]. The reactor was attached to the Omicron Large Sample-UHV/AFM system in the AFM-Lab of the Angewandte Physik-Sensorik chair at the BTU-Cottbus. We investigated different Si(001)/SiO2 substrates and surface preparation techniques performed before the ALD process. After each ALD cycle (using TDMAHf and H2O as precursors), we studied the influence of the HfO2 growth on the root mean square (RMS) roughness; the surface fractal dimension and the height histogram: the surface skewness and kurtosis. We focused on the influence of the substrate temperature on the surface topography during the ALD. The in-situ studies of the ALD process with the UHV/AFM system correlated with the experiments performed with photoelectron spectroscopy can be used for understanding the fundamental properties of the ALD of HfO2 on Si(001). [1] M. Tallarida, K. Karavaev, and D. Schmeisser, J. Appl. Phys. 104, 064116 (2008); [2] M. Tallarida, K. Karavaev, and D. Schmeisser, J. Vac. Sci. Technol. B, accepted for publication.}, language = {en} } @inproceedings{TallaridaKaravaevKolaneketal., author = {Tallarida, Massimo and Karavaev, Konstantin and Kolanek, Krzysztof and Schmeißer, Dieter}, title = {Basics of the atomic layer deposition of HfO2 onto Si/SiO2 substrates: in-situ investigations with XPS, XAS and UHV-AFM}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 44}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 44}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 159}, abstract = {We developed a reactor for investigating in-situ the atomic layer deposition (ALD) of HfO2. X-ray photoelectron and X-ray absorption spectra were collected after each ALD cycle using synchrotron radiation at the beamline U49-2/PGM2 - BESSY II, Berlin. The morphology of the substrate and thin film surfaces was investigated after each ALD cycle with an UHV-AFM microscopy attached to the ALD reactor. We studied the ALD on differently prepared substrates, at different substrate temperatures, and using different Hf-precursors (HfCl4, TEMAHf, TDMAHf). We observed the evolution of the Si/SiO2/HfO2 system during the formation of the first three Hf-oxide layers [1]; we detected the incorporation of Cl into the Hf-oxide films and proposed a mechanism responsible for the Cl contamination [2]; we found evidence of the interfacial-SiO2 growth during the initial ALD cycles and of dipole formation at the HfO2/SiO2 interface. In this contribution we illustrate the basics of the technique used, and discuss the physical-chemical properties of ALD on the basis of the experimental results. [1] M. Tallarida, K. Karavaev, and D. Schmeisser, J. Appl. Phys. 104, 064116 (2008); [2] M. Tallarida, K. Karavaev, and D. Schmeisser, J. Vac. Sci. Technol. B, accepted for publication.}, language = {en} } @inproceedings{TallaridaKaravaevKolaneketal., author = {Tallarida, Massimo and Karavaev, Konstantin and Kolanek, Krzysztof and Schmeißer, Dieter}, title = {In-situ experimental approach to the study of atomic layer deposition with atomic force microscope, X-ray photoelectron and X-ray absorption spectroscopy}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 44}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft ; Reihe 6, Bd. 44}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S.176}, abstract = {We describe our experimental approach to the investigation of atomic layer deposition (ALD). ALD is a powerful deposition technique for growing conformal thin films of composite materials with atomically accurate thickness on large area [1]. Despite the enormous industrial interest growing around ALD, its fundamental properties were not yet properly studied. We developed an ALD reactor for the in-situ investigations using XPS, XAS and AFM as experimental techniques. We studied the chemical-physical properties of the growing thin films after each deposition cycle. Here, we illustrate the recent results concerning the ALD of HfO2 obtained using different Hf-precursors on various substrates [2]. We show how the in-situ investigations could deliver an important insight into the fundamental characteristics of ALD and how these information could be used to modify and optimize the deposition parameters. [1] M. Leskel{\"a}, M. Ritala, Thin Solid Films, 409, 138, 2002; [2] M. Tallarida, K. Karavaev, and D. Schmeisser, J. Appl. Phys. 104, 064116 (2008).}, language = {en} } @inproceedings{MichlingKolanekSchmeisseretal., author = {Michling, Marcel and Kolanek, Krzysztof and Schmeißer, Dieter and Tallarida, Massimo}, title = {A growth model for the HfO2 ALD process}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 294}, abstract = {In this contribution we report on our in-situ2 cycle-by-cycle (up to the 25 cycles) investigation of the HfO2 atomic layer deposition (ALD) process using the method of x-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS). We used Tetrakis-Dimethyl-Amino-Hafnium (TDMA-Hf) and H2O as precursors and p-type Si wafer with native oxide as a substrate. The XPS measurements were carried out at BESSY II in Berlin with primary energies of 150 eV and 640 eV and the EELS measurements were done with a primary energy of 50 eV. We measured the O1s, Si2p core level and the valence band including the Hf 4f core level. From the Hf4f to Si2p ratios taken at each energy we developed a growth model for the first monolayer and for the following layers too. From our data we conclude, that in the first monolayer up to the fourth ALD cycle an island growth occurs. The height of these islands is about 0,5nm. After the first monolayer is completed, a layer- by-layer growth can be expected. In order to proof this observation we have simulated the Hf/Si ratio for different excitation energies and found a very good agreement with our measurement data. The EELS data especially the evaluation of the loss function onset confirm our growth model.}, language = {en} } @inproceedings{TallaridaDessmannStaedteretal., author = {Tallarida, Massimo and Deßmann, Nils and St{\"a}dter, Matthias and Friedrich, Daniel and Michling, Marcel and Schmeißer, Dieter}, title = {Atomic layer deposition of TiO}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 46}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, abstract = {We present a study of the initial growth of TiO2 on Si(111) by atomic layer deposition (ALD). The Si substrate was etched with NH4F before ALD to remove the native oxide film and to produce a Si-H termination. In-situ experiments by means of photoemission and X-ray absorption spectroscopy were conducted with synchrotron radiation on Ti-oxide films produced using Ti-tetra-iso-propoxide (TTIP) and water as precursors. O1s, Ti2p, C1s, and Si2p core level, and O1s and Ti2p absorption edges show the transition of the Ti-oxide properties during the first layers. The growth starts with a very small growth rate (0.03nm/cycle) due to the growth inhibition of the Si-H termination and proceeds with higher growth rate (0.1nm/cycle) after 1.5nm Ti-oxide has been deposited.}, language = {en} } @inproceedings{DasStaedterTallaridaetal., author = {Das, Chittaranjan and St{\"a}dter, Matthias and Tallarida, Massimo and Schmeißer, Dieter}, title = {Investigation of Linear Dichroism in ALD layers of TiO2}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, abstract = {Titanium dioxide is on the most studied material due to its wide range of applications in various fields such as self cleaning, photocatalysis, solar cell, water splitting, bio-implants, etc. In order to increase its efficiency in water splitting and solar cell, it is necessary to understand the crystal structure and electronic properties in thin films. In our approach we are investigating the X-ray linear dichroism (XLD) of thin layers of TiO2. XLD studies have been done in multiferroics, antiferromagnetic, and ferromagnetic materials, but a very less amount of work have been done in studying XLD effect of TiO2 thin films. These layers are grown by in-situ atomic layer deposition (ALD) system and are investigated with X-ray absorption spectroscopy (XAS) at BESSY II, Berlin. ALD is a promising technique to grow thin films on different substrates conveniently due to its uniform deposition property. XAS study will also help us to better understand the interfacial electronic properties of thin films of TiO2.}, language = {en} } @inproceedings{TallaridaMichlingDasetal., author = {Tallarida, Massimo and Michling, Marcel and Das, Chittaranjan and Friedrich, Daniel and St{\"a}dter, Matthias and Schmeißer, Dieter}, title = {Role of substrate chemistry in ALD revealed by in-situ techniques}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 47}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, abstract = {We show recent results of our in-situ investigations where the role of substrate chemistry in ALD is outlined. While the usual strategy to develop new properties of ALD films is to find new precursors or new procedures, the influence of substrate chemistry on the growth properties of ALD films has been often underestimated. This has principally a technical reason, as the usual characterization methods (QMS, FTIR, ellipsometry) are only weakly sensitive to the substrate, and a characterization of substrates before ALD is often not possible. Thanks to the use of in-situ characterization methods, including photoemission and X-ray absorption spectroscopy with synchrotron radiation, we are able to determine chemical properties of substrates before ALD and after either half or complete ALD cycles. The substrate chemistry influences the standard Al2O3 ALD with TMA and water [1,2], as well as the TiO2 ALD with TTIP and either water, O2 or O2-plasma. [1] M. Tallarida, K. Kukli, M. Michling, M. Ritala, M. Leskel{\"a} and D. Schmeisser, Chem. Mater. 23, 3159 (2011); [2] M. Tallarida, C. Adelmann, A. Delabie, S. van Elshocht, M. Caymax, and D. Schmeisser, Appl. Phys. Lett. 92, 042906 (2011).}, language = {en} } @misc{DasTallaridaSchmeisser, author = {Das, Chittaranjan and Tallarida, Massimo and Schmeißer, Dieter}, title = {Si microstructures laminated with a nanolayer of TiO2 as long-term stable and effective photocathodes in PEC devices}, series = {Nanoscale}, journal = {Nanoscale}, number = {7}, issn = {2040-3364}, doi = {10.1039/C5NR00764J}, pages = {7726 -- 7733}, abstract = {Photoelectrochemical (PEC) water splitting is one of the most emerging fields for green energy generation and storage. Here we show a study of microstructured Si covered by a TiO2 nano-layer. The microstructures are prepared by galvanostatic selective etching of Si. The TiO2 nano-layer was deposited by atomic layer deposition (ALD) to protect the microstructured photocathode against corrosion. The obtained microstructured photocathode showed a shift in the onset potential of 400 mV towards the anodic direction compared to bare Si. The Si microstructures laminated with a nano-layer of TiO2 show stability over 60 hours of measurement.}, language = {en} } @inproceedings{HenkelDasSowinskaetal., author = {Henkel, Karsten and Das, Chittaranjan and Sowinska, Małgorzata and Tallarida, Massimo and Schmeißer, Dieter and Gargouri, Hassan and K{\"a}rkk{\"a}nen, Irina and Schneidewind, Jessica and Gruska, Bernd and Arens, Michael}, title = {Charakterisierung von TiO2-ALD-Schichten und deren Nutzung f{\"u}r die Passivierung von Si-Photokathoden}, series = {Tagungsband Photovoltaik-Meeting: Anwendungen-Qualit{\"a}t-Perspektiven, Senftenberg, 15.04.2015}, booktitle = {Tagungsband Photovoltaik-Meeting: Anwendungen-Qualit{\"a}t-Perspektiven, Senftenberg, 15.04.2015}, editor = {Gl{\"u}ck, B. K. and Schmidt, S. and Stein, E. and Raschke, J{\"o}rg-Uwe and Richter, H.}, publisher = {BTU Cottbus-Senftenberg}, address = {Senftenberg}, pages = {3 -- 8}, abstract = {Wir berichten zun{\"a}chst {\"u}ber den Einfluss der Methode der Atomlagenabscheidung auf die TiO2-Schichteigenschaften. Insbesondere wird der Zusammenhang zwischen Ti3+- sowie Interbandzust{\"a}nden mit elektrischen Kennlinien und deren Einfluss auf funktionale Schichteigenschaften diskutiert. Anschließend werden Mikrostrukturierung, Grenzfl{\"a}chen-Engineering und konforme Abscheidung einer TiO2-ALD-Schutzschicht effektiv zur Performance-Steigerung von p-Si-Photokathoden angewendet.}, language = {de} } @misc{NourbakhshAdelmannSongetal., author = {Nourbakhsh, Amirhasan and Adelmann, Christoph and Song, Yi and Lee, Chang Seung and Asselberghs, Inge and Huyghebaert, Cedric and Brizzi, Simone and Tallarida, Massimo and Schmeißer, Dieter and Elshocht, Sven van and Heyns, Marc and Kong, Jing and Palacios, Tom{\´a}s and De Gendt, Stefan}, title = {Graphene oxide monolayers as atomically thin seeding layers for atomic layer deposition of metal oxides}, series = {Nanoscale}, volume = {2015}, journal = {Nanoscale}, number = {7}, issn = {2040-3364}, doi = {10.1039/C5NR01128K}, pages = {10781 -- 10789}, abstract = {Graphene oxide (GO) was explored as an atomically-thin transferable seed layer for the atomic layer deposition (ALD) of dielectric materials on any substrate of choice. This approach does not require specific chemical groups on the target surface to initiate ALD. This establishes GO as a unique interface which enables the growth of dielectric materials on a wide range of substrate materials and opens up numerous prospects for applications. In this work, a mild oxygen plasma treatment was used to oxidize graphene monolayers with well-controlled and tunable density of epoxide functional groups. This was confirmed by synchrotron-radiation photoelectron spectroscopy. In addition, density functional theory calculations were carried out on representative epoxidized graphene monolayer models to correlate the capacitive properties of GO with its electronic structure. Capacitance-voltage measurements showed that the capacitive behavior of Al2O3/GO depends on the oxidation level of GO. Finally, GO was successfully used as an ALD seed layer for the deposition of Al2O3 on chemically inert single layer graphene, resulting in high performance top-gated field-effect transistors.}, language = {en} } @inproceedings{AlbertonCorreaBrizziTallaridaetal., author = {Alberton Corr{\^e}a, Silma and Brizzi, Simone and Tallarida, Massimo and Schmeißer, Dieter}, title = {Charging effect in HfO2 films deposited on SiO2/Si by atomic layer deposition}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, abstract = {Thin films of hafnium oxide (HfO2) deposited by atomic layer deposition (ALD) have been studied extensively as a high-k replacement for the SiO2 gate in field effect transistors. The use of ALD process allows one to grow homogeneous thin films at low temperatures with a precise control of thickness [1]. Some important electrical considerations for the application of a high-k dielectric include the presence of fixed charge (Qf) and charge trapping in the dielectric. For instance, in the case of Al2O3 thin films deposited on Si, the thickness of the interfacial SiO2 layer was identified as a key fundamental parameter determining Qf [2]. A similar trend can be also expected in HfO2/Si structures. Therefore, in this work, we proposed an in situ evaluation of photon induced charge trapping in HfO2 films deposited on SiO2/Si structures. For that, tetrakis-di-methyl-amino-hafnium (TDMAHf) and H2O were employed as precursors to deposit HfO2 films on SiO2/Si samples with variable thickness of the SiO2 interlayer. Measurements were performed by Synchrotron Radiation Photoemission Spectroscopy (SR-PES). Results indicated that the charging process is dependent on the thickness of the SiO2 interlayer and on the quality of the HfO2 film. [1] M. Leskel{\"a} and M. Ritala, Thin Solid Films 409, 138 (2002). [2] G. Dingemans et al., J. Appl. Phys. 110, 093715 (2011).}, language = {en} } @inproceedings{BrizziTallaridaAdelmannetal., author = {Brizzi, Simone and Tallarida, Massimo and Adelmann, Christoph and Ragnarsson, Lars-{\AA}ke and Elshocht, Sven van and Schmeißer, Dieter}, title = {Structural changes in HfO2 thin films: thickness and doping dependence}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, abstract = {In this work we show results regarding MOCVD and ALD HfO2 as well as Al-doped HfO2. We use Synchrotron Radiation Photoemission Spectroscopy (SRPES) to determine Hf/O atomic ratios and X-ray Absorption Spectroscopy (XAS) to investigate the electronic properties related to their crystallization. MOCVD films are synthesized at temperatures ranging from ambient to 400∘C and show structures from completely amorphous to monoclinic. ALD films are amorphous as deposited, and can crystallize after post-deposition anneal depending on the percentage of Al-doping. We discuss PES results in order to determine how close to stoichiometry the Hf/O atomic ratios of the films are, as well as the doping level. From XAS data, instead, we can point out how orbital hybridizations are related to structural and physical properties.}, language = {en} } @inproceedings{DasTallaridaSchmeisser, author = {Das, Chittaranjan and Tallarida, Massimo and Schmeißer, Dieter}, title = {X-ray linear dichroism in atomic layer deposited Titanium dioxide layers}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, abstract = {Among the various metal oxides TiO2 has been investigated because of its wide range of applications in various fields such as self-cleaning, photocatalysis, solar cell, water splitting, bio-implants. In order to increase its efficiency in water splitting and solar cell energy conversion, it is necessary to understand the crystal structure and electronic properties of thin films. Generally the process of synthesis may modify the electronic properties of TiO2. In the present work we show X-ray linear dichroism (XLD) measurements of TiO2 thin films of different polymorphs. Titania thin films were produced by atomic layer deposition (ALD) and were characterized in-situ with X-ray photoelectron and absorption spectroscopy at synchrotron radiation center BESSY-II. We found that that all titania phases show XLD at Ti-L and O-K edges, but the intensity of XLD is different for different phases. We discuss our data in terms of the partial density of states.}, language = {en} } @inproceedings{DasTallaridaSchmeisser, author = {Das, Chittaranjan and Tallarida, Massimo and Schmeißer, Dieter}, title = {Control of thickness of SiO2 interfacial layer for photocatalytic water splitting on Si photocathodes}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, abstract = {Silicon with a band gap of 1.1eV is an excellent candidate for visible photocatalytic water splitting. But p-type Si has a low quantum yield and are less efficient for water splitting [1]. It has been shown that preventing oxidation of Si surface can shift the onset potential for water reduction by about 300mV towards more positive [2]. We investigated in detail the influence of the SiO2 layer thickness on the onset potential for water splitting on Si photocathodes: we used p-type Si substrates covered with SiO2 layers of varying thickness. Then, we deposited a thin TiO2 film on using atomic layer deposition (ALD) to inhibit Si oxidation during the electrochemical experiment. In this way we could shift the onset potential up to 200mV, depending on the SiO2 thickness. [1]E. L. Warren, S. W. Boettcher, M. G. Walter, H. A. Atwater, and N. S. Lewis: J. Phys. Chem. C 115 (2011) 594. [2]B. Seger, Anders B. Laursen, P. C. K. Vesborg, T. Pedersen, O. Hansen, S. Dahl, I. Chorkendorff, Angew. Chem. Int. Ed. 2012, 51, 9128}, language = {en} } @inproceedings{TallaridaHenkelGargourietal., author = {Tallarida, Massimo and Henkel, Karsten and Gargouri, Hassan and Haeberle, J{\"o}rg and Gruska, Bernd and Arens, Matthias and Schmeißer, Dieter}, title = {New opportunities with Plasma enhanced atomic layer deposition (PE-ALD) of oxides}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, abstract = {Thermal Atomic layer deposition (T-ALD) of oxides is obtained by the pulsed alternation of a metal precursor and an oxygen source, typically H2O or O3, and the reactions leading to ALD are thermally activated. With plasma enhanced ALD (PE-ALD), instead, the oxygen source is represented by an oxygen-containing plasma. The higher reactivity of the plasma-generated species extend the capabilities of ALD: improved film quality and increased flexibility in process conditions, such as growth at low temperature, are typical advantages of PE-ALD over T-ALD. We report on results on the preparation of thin (<100 nm) aluminum oxide (Al2O3) films on silicon substrates using T-ALD and PE-ALD in the SENTECH SI ALD LL system. Films were deposited in the temperature range between room temperature (RT) and 200∘C. We characterized the films with spectroscopic ellipsometry (thickness, refractive index, growth rate) over 4" wafers and with X-ray photoelectron spectroscopy. All films resulted in a high degree of homogeneity, independent of the deposition temperature. Investigations with capacitance-voltage and conductance-voltage measurements showed a very low interface states density for the PE-ALD films.}, language = {en} } @inproceedings{AlbertonCorreaBrizziTallaridaetal., author = {Alberton Corr{\^e}a, Silma and Brizzi, Simone and Tallarida, Massimo and Schmeißer, Dieter}, title = {Spectroscopic investigation of the electronic structure of HfO2 thin films}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 211}, abstract = {HfO2 is of current interest as a material for memristive and ferroelectric devices. In this work, we used spectroscopic techniques to evaluate the electronic structure and defects mechanisms in thin HfO2 films deposited by atomic layer deposition and by metal-organic chemical vapour deposition. The partial density of states for the valence and the conduction bands was determined by the detailed analysis of the O1s resonance profile by resonant photoelectron spectroscopy. From the relative contributions we find a CNL 6.5 eV referred to Evac. We also find that the positions of valence band maximum and conduction band minimum, the excitation range for the polaronic states and the range of charge transfer band were not influenced by the preparation conditions. All films exhibit a band gap of 6.2 eV. However, the Fermi level position was found to vary within about 1.2 eV depending on the preparation conditions, which we argue that is due to the presence of charges within the films. This explains why the position of the Fermi level depends on the individual preparation parameters.}, language = {en} } @inproceedings{DasTallaridaSchmeisser, author = {Das, Chittaranjan and Tallarida, Massimo and Schmeißer, Dieter}, title = {Determination of charge neutrality level in TiO2 films from res-PES measurements}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 415}, abstract = {Titanium dioxide is one of the metal oxides which have versatile application in different fields. The applications of TiO2 are in the field of cosmetics, electronics (memory resistive switching), dye, photonics and photocatalysis. In the present paper we study the resPES data of TiO2 films prepared by atomic layer deposition. The measurements are done in in-situ system at beam line U49/2-PGM2 in BESSY-II. The density of state in valence band and conduction band is obtained from the resonance photo electron spectroscopy (res-PES) of the O1s and the Ti2p edge. The data allow to determine the position of the VBM and CBM with respect to the Fermi energy. Also the existence of localized O2p and Ti2p derived states is deduced which appear in the gap. In addition we determine the charge neutrality level (CNL).The CNL is the position where the weight of the density of state from valence band and conduction band are equal. This is an important quantity for the discussion of interface properties.}, language = {en} } @inproceedings{RouissiTallaridaSchmeisser, author = {Rouissi, Zied and Tallarida, Massimo and Schmeißer, Dieter}, title = {Study of atomic layer deposition with scanning tunneling microscopy}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 401}, abstract = {We present a work concerning the study of the initial steps of atomic layer deposition (ALD) with scanning tunneling microscopy (STM). We focus on the role of the substrates which has been often neglected.However, the detailed knowledge of precursor-substrate reactions is important for the understanding of how ALD proceeds. We report on the reaction of the Al-precursor, trimethyl-Al (TMA), on nanostructured surfaces such as Ag nanoclusters and nanostripes prepared by thermal evaporation on HOPG. We characterized the surface before and after one TMA adsorption pulse at room temperature, observing that the morphology of step edges changes after TMA creating a new terraces with a width of 7-10 nm, translated in the direction of the TMA deposition. This shows that, in case of a regular stepped surface, the substrate morphology would keep the same regularity with the translation in a direction privileged by the precursor absorption.}, language = {en} } @inproceedings{RouissiBrizziAlbertonCorreaetal., author = {Rouissi, Zied and Brizzi, Simone and Alberton Corr{\^e}a, Silma and Tallarida, Massimo and Schmeißer, Dieter}, title = {Comparison of charge neutrality level of Cu/CuO/HfO2 and Si/SiO2/HfO2}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {208}, abstract = {Copper Oxide (CuO) is a promising metal oxide semiconductor, which can be used in different applications, such as catalysis, solar energy conversion, and water splitting. In this work, we use resonance photoemission spectroscopy (ResPES) to analyse the electronics properties of HfO2 films deposited on Cu/CuO and Si/SiO2. For that, we deposited 10 cycles of HfO2 by atomic layer deposition (ALD) on Cu/CuO and Si/SiO2 samples and investigated the density states for the valence and conduction bands which were determined by the detailed analysis of the O1s resonance profile obtained by ResPES. We compared the positions of valence band maximum and conduction band minimum, the excitation range for the polaronic states and the range of charge transfer band in Cu/CuO/HfO2 and Si/SiO2/HfO2. Also, we determined the band gap and the charge neutrality level (CNL).}, language = {en} } @misc{DasRichterTallaridaetal., author = {Das, Chittaranjan and Richter, Matthias and Tallarida, Massimo and Schmeißer, Dieter}, title = {Electronic properties of atomic layer deposited films, anatase and rutile TiO2 studied by resonant photoemission spectroscopy}, series = {Journal of Physics D: Applied Physics}, volume = {49}, journal = {Journal of Physics D: Applied Physics}, number = {27}, issn = {0022-3727}, doi = {10.1088/0022-3727/49/27/275304}, pages = {275304-1 -- 275304-17}, abstract = {The TiO2 films are prepared by atomic layer deposition (ALD) method using titanium isopropoxide precursors at 250 °C and analyzed using resonant photoemission spectroscopy (resPES). We report on the Ti2p and O1s core levels, on the valence band (VB) spectra and x-ray absorption spectroscopy (XAS) data, and on the resonant photoelectron spectroscopy (resPES) profiles at the O1s and the Ti3p absorption edges. We determine the elemental abundance, the position of the VB maxima, the partial density of states (PDOS) in the VB and in the conduction band (CB) and collect these data in a band scheme. In addition, we analyze the band-gap states as well as the intrinsic states due to polarons and charge-transfer excitations. These states are found to cause multiple Auger decay processes upon resonant excitation. We identify several of these processes and determine their relative contribution to the Auger signal quantitatively. As our resPES data allow a quantitative analysis of these defect states, we determine the relative abundance of the PDOS in the VB and in CB and also the charge neutrality level. The anatase and rutile polymorphs of TiO2 are analyzed in the same way as the TiO2 ALD layer. The electronic properties of the TiO2ALD layer are compared with the anatase and rutile polymorphs of TiO2. In our comparative study, we find that ALD has its own characteristic electronic structure that is distinct from that of anatase and rutile. However, many details of the electronic structure are comparable and we benefit from our spectroscopic data and our careful analysis to find these differences. These can be attributed to a stronger hybridization of the O2p and Ti3d4s states for the ALD films when compared to the anatase and rutile polymorphs.}, language = {en} } @inproceedings{RouissiTallaridaSchmeisser, author = {Rouissi, Zied and Tallarida, Massimo and Schmeißer, Dieter}, title = {HfO2 grow by ALD on Si(111)-H terminated stepped surface}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, pages = {S. 419}, abstract = {We studied by STM the growth of HfO2 on Si (111)-H stepped surface (miscut by 0.5∘). The steps are aligned in the [11-2] direction. In order to obtain well defined steps and terraces we prepare the sample by chemical etching in 40\% Nh4F. In our in-situ study we investigate the ALD growth of HfO2 by TDMAH and H2O [1-2]. We follow for the first four ALD cycles the distribution of the nucleation sites. We also study the influence of the substrate temperature by comparing the growth within the ALD window at 300K and 580K. We observed that at RT the as-grown HfO2 forms stripes which are oriented normal to the step orientations. Further growth starts from the step edges and proceeds towards the terraces. Defects created by the etching processes act as nucleation sites for 3D islands. Based on our STM data we are able to correlate the structural changes on that inert and stepped Si(111)-H surface during ALD with experimental [3] and theoretical [4] results obtained for planar Si(100) surfaces. [1] M. Tallarida et al., Semicond. Sci. Technol. 27, 074010 (2012) [2] K. Kolanek et al., Thin Solid Films 518, 4688 (2010) [3] K. Kolanek et al., J. Vac. Sci. Technol. A 31, 01A104 (2013) [4]L. Riikka et al., J. Appl. Phys.96, 7686 (2004)}, language = {en} }