@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} } @misc{KotWojciechowskiSnaithetal., author = {Kot, Małgorzata and Wojciechowski, Konrad and Snaith, Henry J. and Schmeißer, Dieter}, title = {Evidence of Nitrogen Contribution to the Electronic Structure of the CH₃NH₃PbI₃ Perovskite}, series = {Chemistry - A European Journal}, volume = {24}, journal = {Chemistry - A European Journal}, number = {14}, issn = {0947-6539}, doi = {10.1002/chem.201705144}, pages = {3539 -- 3544}, abstract = {Despite fast development of hybrid perovskite solar cells, there are many fundamental questions related to the perovskite film which remain open. For example, there are contradicting theoretical reports on the role of the or-ganic methylammonium cation (CH₃NH₃+)in the methylam-monium lead triiodide (CH₃NH₃PbI₃)perovskite film. From one side it is reported that the organic cation does not contribute to electronic structure of the CH₃NH₃PbI₃ film. From the other side, valence band maximum fluctuations, dependent on the CH₃NH₃+ rotation, have been theoretically predicted. The resonant X-ray photoelectron spectroscopy results reported here show experimental evidence of nitrogen contribution to the CH₃NH₃PbI₃ electronic structure. Moreover,the observed strong resonances of nitrogen with the I 5s and the Pb 5d-6s levels indicate that the CH₃NH₃PbI₃ valence band is extended up to ~18 eV below the Fermi energy, and therefore one should also consider these shallow core levels while modeling its electronic structure.}, 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} } @inproceedings{KotKegelmannKusetal., author = {Kot, Małgorzata and Kegelmann, Lukas and Kus, Peter and Tsud, Nataliya and Matol{\´i}nov{\´a}, Iva and Albrecht, Steve and Matolin, Vladimir and Schmeißer, Dieter}, title = {Room temperature atomic layer deposition for perovskite solar cells}, 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. 174}, abstract = {After few years of efficiency driven research on perovskite solar cells, the focus now is shifting to understand the underlying processes governing the high efficiency and also to obtain long-term stable devices. Among various deposition methods, atomic layer deposition (ALD) may represent one of the best options, being possible to coat substrates in a very efficient way and at very low temperatures. In our previous work [1] we reported that the efficiency of the solar cell containing aged perovskite film can be enhanced twice while covering the perovskite with a thin ALD alumina film at room temperature. In this work, the chemical, electronic and morphological properties of the fresh perovskite film treated by ALD pulses of the trimethylaluminium and water at room temperature investigated using X-ray Photoelectron Spectroscopy and Field Emission Scanning Electron Microscopy will be discused and correlated with the solar cells performance and stability. [1] M. Kot et al., ChemSusChem 2016, 9, 3401.}, language = {en} } @incollection{HenkelKotRichteretal., author = {Henkel, Karsten and Kot, Małgorzata and Richter, Matthias and Tallarida, Massimo and Schmeißer, Dieter}, title = {An (In Situ)² Approach: ALD and resPES Applied to Al₂O₃, HfO₂, and TiO₂ Ultrathin Films}, series = {Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry, Vol. 3.1}, booktitle = {Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry, Vol. 3.1}, editor = {Wandelt, Klaus}, publisher = {Elsevier}, address = {Oxford}, isbn = {978-0-12-809739-7}, doi = {10.1016/B978-0-12-409547-2.13852-1}, pages = {18 -- 26}, abstract = {Oxide surface coatings are of importance in tailoring interface properties with respect to surface passivation, adjustment of surface potentials, or providing active centers for surface reactions. In this contribution, we report about surface coatings prepared by the atomic layer deposition (ALD) method. ALD is known for its conformal growth of ultrathin, dense films which exhibit a low concentration of pinholes.}, language = {en} } @incollection{SchmeisserKotCorreaetal., author = {Schmeißer, Dieter and Kot, Małgorzata and Corr{\^e}a, Silma Alberton and Das, Chittaranjan and Henkel, Karsten}, title = {Interface Potentials, Intrinsic Defects, and Passivation Mechanisms in Al₂O₃, HfO₂, and TiO₂ Ultrathin Films}, series = {Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry, vol. 3.1}, booktitle = {Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry, vol. 3.1}, editor = {Wandelt, Klaus}, publisher = {Elsevier}, address = {Oxford}, isbn = {978-0-12-809739-7}, doi = {10.1016/B978-0-12-409547-2.14119-8}, pages = {162 -- 171}, abstract = {We study the electronic structure of ultrathin Al₂O₃, HfO₂, and TiO₂ ALD films by resonant photoelectron spectroscopy. We identify intrinsic defects which are responsible for the active sites in interface reactions, for the incorporation of intrinsic charges, and for the formation of local dipole momenta. All of these features determine the surface potentials and the reactivity of the surface of the atomic layer deposition coated systems. We give examples of charges and dipoles in Al₂O₃, on a study of the surface potentials in HfO₂, and relate the intrinsic defects in TiO₂ to their electrochemical relevance.}, language = {en} } @misc{KotKegelmannDasetal., author = {Kot, Małgorzata and Kegelmann, Lukas and Das, Chittaranjan and Kus, Peter and Tsud, Nataliya and Matol{\´i}nov{\´a}, Iva and Albrecht, Steve and Matolin, Vladimir and Schmeißer, Dieter}, title = {Room temperature atomic layer deposited Al₂O₃ improves perovskite solar cells efficiency over time}, series = {ChemSusChem}, volume = {11}, journal = {ChemSusChem}, number = {20}, issn = {1864-5631}, doi = {10.1002/cssc.201801434}, pages = {3640 -- 3648}, abstract = {Electrical characterisation of perovskite solar cells consisting of room-temperature atomic-layer-deposited aluminium oxide (RT-ALD-Al₂O₃) film on top of a methyl ammonium lead triiodide (CH₃NH₃PbI₃) absorber showed excellent stability of the power conversion efficiency (PCE) over along time. Under the same environmental conditions (for 355 d), the average PCE of solar cells without the ALD layer decreased from 13.6 to 9.6 \%, whereas that of solar cells containing 9 ALD cycles of depositing RT-ALD-Al₂O₃on top of CH₃NH₃PbI₃ increased from 9.4 to 10.8 \%. Spectromicroscopic investigations of the ALD/perovskite interface revealed that the maximum PCE with the ALD layer is obtained when the so-called perovskite cleaning process induced by ALD precursors is complete. The PCE enhancement over time is probably related to a self-healing process induced by the RT-ALD-Al₂O₃ film. This work may provide a new direction for further improving the long-term stability and performance of perovskite solar cells.}, 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{KotwicaDomaradzkiWojcieszaketal., author = {Kotwica, Tomasz and Domaradzki, Jarosław and Wojcieszak, Damian and Sikora, Andrzej and Kot, Małgorzata and Schmeißer, Dieter}, title = {Analysis of surface properties of Ti-Cu-Ox gradient thin films using AFM and XPS investigations}, series = {Materials Science-Poland}, volume = {36}, journal = {Materials Science-Poland}, number = {4}, issn = {0137-1339}, doi = {10.2478/msp-2018-0100}, pages = {761 -- 768}, abstract = {The paper presents results of investigations on surface properties of transparent semiconducting thin films based on (Ti-Cu)oxide system prepared using multi-magnetron sputtering system. The thin films were prepared using two programmed profiles of pulse widt hmodulation coefficient, so called V- and U-shape profiles. The applied powering profiles allowed fabrication of thin films with gradient distribution of Ti and Cu elements over the thickness of deposited layers. Optical investigations allowed determination of transparency of prepared films that reached up to 60 \% in the visible part of optical radiation, which makes them attractive for the transparent electronics domain. Surface properties investigations showed that the surface of mixed (Ti-Cu)oxides was sensitive to adsorption, in particular to carbon dioxide and water vapor. Soft etching with argon ions resulted in surface cleaning from residuals, however, deoxidation of Cu-oxide components was also observed.}, language = {en} } @misc{ObstarczykKaczmarekWojcieszaketal., author = {Obstarczyk, Agata and Kaczmarek, Danuta and Wojcieszak, Damian and Mazur, Michał and Domaradzki, Jarosław and Kotwica, Tomasz and Pastuszek, Roman and Schmeißer, Dieter and Mazur, Piotr and Kot, Małgorzata}, title = {Tailoring optical and electrical properties of thin-film coatings based on mixed Hf and Ti oxides for optoelectronic application}, series = {Materials and Design}, volume = {175}, journal = {Materials and Design}, issn = {0264-1275}, doi = {10.1016/j.matdes.2019.107822}, pages = {15}, abstract = {In this work multi-magnetron sputtering stand was used for the deposition of the mixed oxides thin films based on HfO2 and TiO2. In order to obtain various material composition the power released to each magnetron (containing metallic hafnium and titanium targets) was precisely selected. Structural, surface, optical, electrical and mechanical properties of as-deposited coatings were analyzed. Depending on the hafnium content in the deposited thin films various types of the microstructure was obtained, i.e. HfO2-monoclinic, amorphous and TiO2-rutile. Increase of Ti content above 28 at. \% in the as-prepared mixed oxides coatings caused their amorphization. It was found that with an increase of Ti content in prepared coatings their surface roughness and simultaneously water contact angle decreased. Performed measurements of electrical properties revealed that the lowest leakage current density in the range of 10-7 - 10-8 A/cm2 was obtained for amorphous coatings. Moreover, the tailoring of the dielectric constant was possible by a proper selection of material composition and microstructure of the deposited thin films. Average transparency in the visible wavelength region was in the range of ca. 79-86\%. The influence of material composition and structure on shifting of the fundamental absorption edge and optical bandgap energy was also observed. The refractive index increased with an increase of Ti content, while extinction coefficient was the lowest for amorphous coatings. Additionally, hardness values were dependent on the material composition and optical packing density and were in the range from 7.6 GPa to 10.1 GPa.}, language = {en} }