@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{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{SowińskaHenkelSchmeisseretal., author = {Sowińska, Małgorzata and Henkel, Karsten and Schmeißer, Dieter and K{\"a}rkk{\"a}nen, Irina and Schneidewind, Jessica and Naumann, Franziska and Gruska, Bernd and Gargouri, Hassan}, title = {Plasma-enhanced atomic layer deposition of titanium oxynitrides films: A comparative spectroscopic and electrical study}, series = {Journal of Vacuum Science and Technology A}, journal = {Journal of Vacuum Science and Technology A}, number = {34}, issn = {0734-2101}, doi = {10.1116/1.4936227}, pages = {01A127-1 -- 01A127-9}, abstract = {The process parameters' impact of the plasma-enhanced atomic layer deposition (PE-ALD) method on the oxygen to nitrogen (O/N) ratio in titanium oxynitride (TiOxNy) films was studied. Titanium(IV)isopropoxide in combination with NH3 plasma and tetrakis(dimethylamino) titanium by applying N2 plasma processes were investigated. Samples were characterized by the in situ spectroscopic ellipsometry, x-ray photoelectron spectroscopy, and electrical characterization (current-voltage: I-V and capacitance-voltage: C-V) methods. The O/N ratio in the TiOxNy films is found to be very sensitive for their electric properties such as conductivity, dielectric breakdown, and permittivity. Our results indicate that these PE-ALD film properties can be tuned, via the O/N ratio, by the selection of the process parameters and precursor/coreactant combination.}, language = {en} } @misc{SowinskaBrizziDasetal., author = {Sowinska, Małgorzata and Brizzi, Simone and Das, Chittaranjan and K{\"a}rkk{\"a}nen, Irina and Schneidewind, Jessica and Naumann, Franziska and Gargouri, Hassan and Henkel, Karsten and Schmeißer, Dieter}, title = {Analysis of nitrogen species in titanium oxynitride ALD films}, series = {Applied Surface Science}, volume = {381}, journal = {Applied Surface Science}, issn = {0169-4332}, doi = {10.1016/j.apsusc.2016.02.096}, pages = {42 -- 47}, abstract = {Titanium oxynitride films are prepared by plasma enhanced atomic layer deposition method using two different precursors and nitrogen sources. Synchrotron radiation-based X-ray photoelectron spectroscopy and X-ray absorption spectroscopy are used to characterize the nitrogen species incorporated within these films depending on the deposition parameters. It is found that nitrogen atoms in these films are differently bonded. In particular, it can be distinguished between Ti-ON and Ti-N bonding configurations and molecular nitrogen species caused by precursor fragments.}, language = {en} } @misc{HenkelDasKotetal., author = {Henkel, Karsten and Das, Chittaranjan and Kot, Małgorzata and Schmeißer, Dieter and Naumann, Franziska and K{\"a}rkk{\"a}nen, Irina and Gargouri, Hassan}, title = {In-gap states in titanium dioxide and oxynitride atomic layer deposited films}, series = {Journal of Vacuum Science and Technology: A}, volume = {35}, journal = {Journal of Vacuum Science and Technology: A}, number = {1}, issn = {0734-2101}, doi = {10.1116/1.4972247}, pages = {01B135-1 -- 01B135-8}, abstract = {Valence band (VB) spectra of titanium dioxide (TiO2) and oxynitride (TiOxNy) films prepared by different atomic layer deposition (ALD) processes are compared and related to electrical characterization [current-voltage (JV) and capacitance-voltage (CV)] results. By increasing the nitrogen amount in the TiO2 film, band-gap narrowing is observed. The band-gap decrease is related to the contribution of the nitrogen density of states, which induces defects within the band-gap and thus reduces its optical band-gap. In-gap states are found in the VB spectra at 1 eV below the Fermi energy in all investigated ALD samples, i.e., in TiO2 as well as in TiOxNy films. An exponential correlation between leakage current density and in-gap state intensity is derived by the combination of JV measurements and VB spectra, whereas the in-gap states seem to have no influence on hysteresis and fixed oxide charges found in the CV data. It is argued that the in-gap states in TiO2 and TiOxNy have an excitonic or polaronic origin. Both, band-gap narrowing and in-gap state intensity can be tuned by the ALD process selection and the variation of its parameters.}, language = {en} } @misc{KotHenkelDasetal., author = {Kot, Małgorzata and Henkel, Karsten and Das, Chittaranjan and Brizzi, Simone and K{\"a}rkk{\"a}nen, Irina and Schneidewind, Jessica and Naumann, Franziska and Gargouri, Hassan and Schmeißer, Dieter}, title = {Analysis of titanium species in titanium oxynitride films prepared by plasma enhanced atomic layer deposition}, series = {Surface and Coatings Technology}, volume = {324}, journal = {Surface and Coatings Technology}, issn = {0257-8972}, doi = {10.1016/j.surfcoat.2016.11.094}, pages = {586 -- 593}, abstract = {A comparative study of thin titanium oxynitride (TiOxNy) films prepared by plasma enhanced atomic layer deposition using tetrakis(dimethylamino)titanium (TDMAT) and N2 plasma as well as titanium(IV)isopropoxide and NH3 plasma is reported. The comparison is based on the combination of Ti2p core level and valence band spectroscopy and current-voltage measurements. The TDMAT/N2 process delivers generally higher fractions of TiN and TiON within the Ti2p spectra of the films and stronger photoemissions within the bandgap as resolved in detail by high energy resolution synchrotron-based spectroscopy. In particular, it is shown that higher TiN contributions and in-gap emission intensities correlate strongly with increased leakage currents within the films and might be modified by the process parameters and precursor selection.}, language = {en} } @misc{KotŁobazaNaumannetal., author = {Kot, Małgorzata and Łobaza, Justyna and Naumann, Franziska and Gargouri, Hassan and Henkel, Karsten and Schmeißer, Dieter}, title = {Long-term ambient surface oxidation of titanium oxynitride films prepared by plasma-enhanced atomic layer deposition: An XPS study}, series = {Journal of Vacuum Science and Technology A}, volume = {36}, journal = {Journal of Vacuum Science and Technology A}, number = {1}, issn = {0734-2101}, doi = {10.1116/1.5003356}, abstract = {The surface oxidation of a titanium oxynitride (TiOxNy) film after long-time storage of 25 month in ambient conditions is investigated. The TiOxNy film is prepared by plasma-enhanced atomic layer deposition using etrakis(dimethylamino)titanium and nitrogen plasma, and the film is characterized by Ar+ ion sputtering of the film surface in combination with x-ray photoelectron spectroscopy (XPS) as well as by angle-resolved XPS. The total thickness of an oxygen-enriched layer at the surface of the TiOxNy films is found to be about 0.7 nm and it consists of a sequence of a 0.4 nm thick TiON/TiO2 enriched layer followed by a 0.3 nm thick TiO2 enriched layer underneath compared to the bulk composition of the film which shows constant values of 29\% TiN, 29\% TiO2, and 42\% TiON. The results suggest that the TiON enrichment takes place initially at the surface followed by a surface and subsurface oxidation.}, language = {en} } @inproceedings{KotNaumannGarainetal., author = {Kot, Małgorzata and Naumann, Franziska and Garain, Samiran and Po{\'{z}}arowska, Emilia and Gargouri, Hassan and Henkel, Karsten and Schmeißer, Dieter}, title = {Aluminum nitride films prepared by plasma atomic layer deposition using different plasma sources}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Band 53,3}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Band 53,3}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 170}, abstract = {Aluminum nitride (AlN) thin films are promising for versatile applications in optoelectronics, electronics, piezoelectrics, and acoustics due to their remarkable properties such as wide band gap, high dielectric constant, low electrical conductivity, good piezoelectric coefficient and high ultrasonic velocity. We present a comparative study of AlN films grown by plasma-enhanced atomic layer deposition at 350°C silicon wafers in the SENTECH SI ALD LL system using TMA and NH3 where either a capacitively coupled plasma (CCP) or a direct PTSA (planar triple spiral antenna) source was applied. The films were characterized by ellipsometry, XPS and electrical measurements. The layer properties are discussed concerning the varied ALD process parameters. In general, the process using the direct PTSA source delivered films with higher refractive index and better homogeneity over the wafer achieving also higher growth rates per cycle (GPC) in reduced total cycle durations. Films with refractive index in the range of 2.05 and permittivity around 8 could be realized with a GPC of 1.54 {\AA}/cycle.}, language = {en} } @misc{KotHenkelNaumannetal., author = {Kot, Małgorzata and Henkel, Karsten and Naumann, Franziska and Gargouri, Hassan and Tarnawska, Lidia Lupina and Wilker, Viola and Kus, Peter and Pożarowska, Emilia and Garain, Samiran and Rouissi, Zied and Schmeißer, Dieter}, title = {Comparison of plasma-enhanced atomic layer deposition AlN films prepared with different plasma sources}, series = {Journal of Vacuum Science and Technology A}, volume = {37}, journal = {Journal of Vacuum Science and Technology A}, number = {2}, issn = {0734-2101}, doi = {10.1116/1.5079628}, pages = {11}, abstract = {A comparative study of thin aluminum nitride (AlN) films deposited by plasma-enhanced atomic layer deposition in the SENTECH SI ALD LL system applying either a direct inductively coupled plasma (ICP) or an indirect capacitively coupled plasma (CCP) source is presented. The films prepared with the ICP source (based on a planar triple spiral antenna) exhibit improved properties concerning the growth rate per cycle, total cycle duration, homogeneity, refractive index, fixed and mobile electrical charges, and residual oxygen content compared to the CCP source, where the comparison is based on the applied plasma power of 200 W. The increase of the plasma power to 600 W in the ICP process significantly reduces the residual oxygen content and enhances the electrical breakdown field. The AlN layers grown under these conditions, with a growth rate per cycle of 1.54 {\AA}/cycle, contain residual oxygen and carbon concentrations of about 10\% and 4\%, respectively, and possess a refractive index of 2.07 (at 632.8 nm).}, language = {en} } @misc{NaumannReckGargourietal., author = {Naumann, Franziska and Reck, Johanna and Gargouri, Hassan and Gruska, Bernd and Bl{\"u}mich, Adrian and Mahmoodinezhad, Ali and Janowitz, Christoph and Henkel, Karsten and Flege, Jan Ingo}, title = {In situ real-time and ex situ spectroscopic analysis of Al₂O₃ films prepared by plasma enhanced atomic layer deposition}, series = {Journal of Vacuum Science and Technology B}, volume = {38}, journal = {Journal of Vacuum Science and Technology B}, number = {1}, issn = {0734-211X}, doi = {10.1116/1.5122797}, pages = {10}, abstract = {In situ real-time ellipsometry (irtE) with a very high time resolution of 24 ms was applied to monitor the inductively coupled plasma enhanced atomic layer deposition (ALD) process of Al₂O₃ thin films to precisely resolve each step of the ALD process and its complete cycle. The influence of plasma power, plasma pulse duration, and deposition temperature on the film growth characteristics was investigated. Ex situ ellipsometry [UV-VIS-NIR-SE (ultraviolet-visible-nearinfrared-spectroscopic ellipsometry) and IR-SE (infrared spectroscopic ellipsometry)] and x-ray photoelectron spectroscopy revealed the bulk properties (thickness, refractive index, chemical composition, and carbon incorporation) of the films, which together with the in situ results are compared to those of the films prepared by thermal ALD (T-ALD). The ICPEALD (inductively coupled plasma enhanced ALD) films were deposited at substrate temperatures between 80 and 250 °C and the role of plasma power (50-300 W) and its pulse duration (1-20 s) was investigated at 250 °C. The reference T-ALD layers were prepared at 200 °C. The ICPEALD process of Al₂O₃ shows an increased growth rate, and the produced films exhibit higher carbon contaminations than the T-ALD Al₂O₃ films. Plasma pulse times of up to 15 s further increase the content of carbon and CH species; at the same time, the refractive index decreases. The optical properties of ICPEALD deposited Al₂O₃ films are comparable with those of the T-ALD films for low plasma power and short plasma pulse durations. For the ICPEALD films, UV absorption is found and it is dependent on the deposition parameters. irtE resolves process effects that correlate with the bulk properties of Al₂O₃, such as impurities and oxygen deficiencies.}, language = {en} } @misc{MahmoodinezhadJanowitzNaumannetal., author = {Mahmoodinezhad, Ali and Janowitz, Christoph and Naumann, Franziska and Plate, Paul and Gargouri, Hassan and Henkel, Karsten and Schmeißer, Dieter and Flege, Jan Ingo}, title = {Low-temperature growth of gallium oxide thin films by plasma-enhanced atomic layer deposition}, series = {Journal of Vacuum Science and Technology A}, volume = {38}, journal = {Journal of Vacuum Science and Technology A}, number = {2}, issn = {0734-2101}, doi = {10.1116/1.5134800}, abstract = {Gallium oxide (Ga2O3) thin films were deposited by plasma-enhanced atomic layer deposition (PEALD) applying a capacitively coupled plasma source where trimethylgallium (TMGa) as the gallium precursor and oxygen (O2) plasma were used in a substrate temperature (Ts)in the range of 80-200 °C. TMGa exhibits high vapor pressure and therefore facilitates deposition at lower substrate temperatures. The Ga2O3 films were characterized by spectroscopic ellipsometry (SE), x-ray photoelectron spectroscopy (XPS), and capacitance-voltage (C-V) measurements. The SE data show linear thickness evolution with a growth rate of ∼0.66 {\AA} per cycle and inhomogeneity of ≤2\% for all samples. The refractive index of the Ga2O3 thin films is 1.86 ± 0.01 (at 632.8 nm) and independent of temperature, whereas the bandgap slightly decreases from 4.68 eV at Ts of 80 °C to 4.57 eV at 200 °C. XPS analysis revealed ideal stoichiometric gallium to oxygen ratios of 2:3 for the Ga2O3 layers with the lowest carbon contribution of ∼10\% for the sample prepared at 150 °C. The permittivity of the layers is 9.7 ± 0.2 (at 10 kHz). In addition, fixed and mobile oxide charge densities of 2-4E12 and 1-2E12 cm-2, respectively, were observed in the C-V characteristics. Moreover, the Ga2O3 films show breakdown fields in the range of 2.2-2.7 MV/cm. Excellent optical and electrical material properties are maintained even at low substrate temperatures as low as 80 °C. Hence, the TMGa/O2 PEALD process is suitable for electronic and optoelectronic applications where low-temperature growth is required.}, language = {en} } @misc{JanowitzMahmoodinezhadNaumannetal., author = {Janowitz, Christoph and Mahmoodinezhad, Ali and Naumann, Franziska and Plate, Paul and Henkel, Karsten and Flege, Jan Ingo}, title = {XPS and UPS investigation of an ALD prepared Al2O3/ZnO heterojunction}, series = {Verhandlungen der DPG - SurfaceScience21}, volume = {2021}, journal = {Verhandlungen der DPG - SurfaceScience21}, publisher = {Deutsche Physikalische Gesellschaft e.V.}, address = {Bad Honnef}, abstract = {The band alignment of two large band gap oxides was studied by a combination of XPS and UPS using consecutive sputter steps to unravel the electronic structure and elemental composition of each layer and the interface region. An Al2O3/ZnO heterointerface (10 nm Al2O3 on 59 nm ZnO) was grown on top of a Si single crystal substrate by consecutive thermal and plasma-assisted atomic layer deposition (ALD) respectively. The valence band maximum of Al2O3 was found to be 1.1 eV below that of ZnO, the conduction band minimum 2.3 eV above, resulting in a type-I staggered heterojunction. A reduction of ZnO to elemental Zn in the interface region was detected by the apparent shoulder of the Zn 2p and 2s core levels and by the Zn LMM Auger. This suggests an ALD interface formation mechanism different from previous models identified for other heterointerfaces.}, language = {en} } @misc{MahmoodinezhadMoralesNaumannetal., author = {Mahmoodinezhad, Ali and Morales, Carlos and Naumann, Franziska and Plate, Paul and Meyer, Robert and Janowitz, Christoph and Henkel, Karsten and Kot, Małgorzata and Flege, Jan Ingo}, title = {Low-temperature atomic layer deposition of indium oxide thin films using trimethylindium and oxygen plasma}, series = {Verhandlungen der DPG - SurfaceScience21}, volume = {2021}, journal = {Verhandlungen der DPG - SurfaceScience21}, publisher = {Deutsche Physikalische Gesellschaft e.V.}, address = {Bad Honnef}, abstract = {Indium oxide thin films were deposited on Si (100) by plasma-enhanced atomic layer deposition (PEALD) using trimethylindium (TMIn) and oxygen plasma (O2) in a low-temperature range of 80 to 200 °C. The In2O3 layers were characterized by in-situ spectroscopic ellipsometry (SE), ex-situ X-ray photoelectron spectroscopy (XPS) and electrical measurements. The SE data show a growth rate of 0.56 {\AA}/cycle within the ALD window (100 to 150 °C) with a thickness inhomogeneity of ≤1.2\%. In addition, the highest refractive index is 2.07 (at 632.8 nm) for the layer grown at 150 °C, and the films exhibit indirect and direct band gaps of 2.8±0.1 eV and 3.3±0.2 eV, respectively. XPS characterization indicates no carbon incorporation and a temperature-dependent off-stoichiometry of the layers. The chemical analysis of the In 3d and O 1s core levels confirms the formation of In-O bonds and suggests the additional presence of hydroxyl groups and defects. With increasing temperature, the contribution of OH groups and defects decreases whereas that of In-O bonds increases. Notably, higher growth temperatures result in an indium rich phase within the layers.}, language = {en} } @misc{MahmoodinezhadMoralesNaumannetal., author = {Mahmoodinezhad, Ali and Morales, Carlos and Naumann, Franziska and Plate, Paul and Meyer, Robert and Janowitz, Christoph and Henkel, Karsten and Kot, Małgorzata and Z{\"o}llner, Marvin Hartwig and Wenger, Christian and Flege, Jan Ingo}, title = {Low-temperature atomic layer deposition of indium oxide thin films using trimethylindium and oxygen plasma}, series = {Journal of Vacuum Science and Technology A}, volume = {39}, journal = {Journal of Vacuum Science and Technology A}, number = {6}, issn = {0734-2101}, doi = {10.1116/6.0001375}, abstract = {Indium oxide (InxOy) thin films were deposited by plasma-enhanced atomic layer deposition (PEALD) using trimethylindium and oxygen plasma in a low-temperature range of 80-200 °C. The optical properties, chemical composition, crystallographic structure, and electrical characteristics of these layers were investigated by spectroscopic ellipsometry (SE), x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), as well as current-voltage and capacitance-voltage measurements. The SE results yielded a nearly constant growth rate of 0.56 {\AA} per cycle and a thickness inhomogeneity of ≤1.2\% across 4-in. substrates in the temperature range of 100-150 °C. The refractive index (at 632.8 nm) was found to be 2.07 for the films deposited at 150 °C. The PEALD-InxOy layers exhibit a direct (3.3 ± 0.2 eV) and an indirect (2.8 ± 0.1 eV) bandgap with an uptrend for both with increasing substrate temperature. Based on XPS characterization, all InxOy samples are free of carbon impurities and show a temperature-dependent off-stoichiometry indicating oxygen vacancies. XRD diffraction patterns demonstrate an onset of crystallization at 150 °C. Consistent with the optical, XPS, and XRD data, the films deposited at ≥150 °C possess higher electrical conductivity. Our findings prove that a low-temperature PEALD process of InxOy is feasible and promising for a high-quality thin-film deposition without chemical impurities on thermally fragile substrates.}, language = {en} } @misc{JanowitzMahmoodinezhadKotetal., author = {Janowitz, Christoph and Mahmoodinezhad, Ali and Kot, Małgorzata and Morales, Carlos and Naumann, Franziska and Plate, Paul and Z{\"o}llner, Marvin Hartwig and B{\"a}rwolf, Florian and Stolarek, David and Wenger, Christian and Henkel, Karsten and Flege, Jan Ingo}, title = {Toward controlling the Al2O3/ZnO interface properties by in situ ALD preparation}, series = {Dalton Transactions}, volume = {51}, journal = {Dalton Transactions}, issn = {1477-9234}, doi = {10.1039/D1DT04008A}, pages = {9291 -- 9301}, abstract = {An Al2O3/ZnO heterojunction was grown on a Si single crystal substrate by subsequent thermal and plasma-assisted atomic layer deposition (ALD) in situ. The band offsets of the heterointerface were then studied by consecutive removal of the layers by argon sputtering, followed by in situ X-ray photoelectron spectroscopy. The valence band maximum and conduction band minimum of Al2O3 are found to be 1.1 eV below and 2.3 eV above those of ZnO, resulting in a type-I staggered heterojunction. An apparent reduction of ZnO to elemental Zn in the interface region was detected in the Zn 2p core level and Zn L3MM Auger spectra. This suggests an interface formation different from previous models. The reduction of ZnO to Zn in the interface region accompanied by the creation of oxygen vacancies in ZnO results in an upward band bending at the interface. Therefore, this study suggests that interfacial properties such as the band bending as well as the valence and conduction band offsets should be in situ controllable to a certain extent by careful selection of the process parameters.}, language = {en} } @misc{MoralesPlateMarthetal., author = {Morales, Carlos and Plate, Paul and Marth, Ludwig and Naumann, Franziska and Kot, Małgorzata and Janowitz, Christoph and Kus, Peter and Z{\"o}llner, Marvin Hartwig and Wenger, Christian and Henkel, Karsten and Flege, Jan Ingo}, title = {Bottom-up design of a supercycle recipe for atomic layer deposition of tunable Indium Gallium Zinc Oxide thin films}, series = {ACS Applied Electronic Materials}, volume = {6}, journal = {ACS Applied Electronic Materials}, number = {8}, publisher = {American Chemical Society (ACS)}, issn = {2637-6113}, doi = {10.1021/acsaelm.4c00730}, pages = {5694 -- 5704}, abstract = {We present a successful bottom-up approach to design a generic plasma-enhanced atomic layer deposition (PEALD) supercycle recipe to grow high-quality indium gallium zinc oxide (IGZO) thin films with tunable composition at a relatively low temperature of 150 °C. In situ real-time ellipsometric characterization in combination with ex situ complementary techniques has been used to optimize the deposition process and quality of the films by identifying and solving growth challenges such as degree of oxidation, nucleation delays, or elemental composition. The developed supercycle approach enables facile control of the target composition by adapting the subcycle ratios within the supercycle process. Compared to other low-temperature deposition techniques resulting in amorphous films, our PEALD-IGZO process at 150 °C results in nearly amorphous, nanocrystalline films. The preparation of IGZO films at low temperature by a supercycle PEALD approach allows controlling the thickness, composition, and electrical properties while preventing thermally induced segregation.}, language = {en} } @misc{MahmoodinezhadMoralesKotetal., author = {Mahmoodinezhad, Ali and Morales, Carlos and Kot, Małgorzata and Naumann, Franziska and Plate, Paul and Henkel, Karsten and Flege, Jan Ingo}, title = {A super-cycle approach to atomic layer deposition of indium-gallium-zinc oxide at low temperature}, series = {Verhandlungen der DPG}, journal = {Verhandlungen der DPG}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, abstract = {The continuing development of multifunctional devices needs novel multicomponent oxide layers, demanding a high control of both composition and thickness during their preparation. To this end, single metal oxides exhibiting high structural quality and conformity have successfully been grown by atomic layer deposition (ALD). However, the deposition of more complex compounds with specific optical and electrical properties is still challenging. In this work, we follow a bottom-up approach to design an ALD super-cycle to grow mixed indium-gallium-zinc oxide (IGZO) films with a controllable composition. For the formation of the individual indium, gallium, and zinc oxides, we found the use of plasma-enhanced ALD (PEALD) at 150 °C to be favorable when using the organometallic precursors trimethylindium, trimethylgallium, and diethylzinc together with oxygen plasma. The PEALD approach of IGZO films can particularly overcome a nucleation delay within the ZnO sub-cycle known from thermal ALD, achieving a higher growth per cycle and improving the quality and composition homogeneity of the films as shown by in-situ spectroscopic ellipsometry and ex-situ X-ray photoelectron spectroscopy.}, language = {en} }