Aluminum-doped zinc oxide (AZO) is one of the most promising transparent conductive oxide (TCO) materials that can substitute the high-quality but costly indium tin oxide (ITO). To ensure high-quality films as well as moderate production costs, inline DC magnetron sputtering was chosen to deposit thin AZO films. The influence of sputter gas pressure, substrate temperature, and film thickness on the electrical, optical, and structural properties was analyzed. The resistivity reaches a minimum of 1.3×10-5 Ωm at around 1 Pa for a substrate temperature of 90°C. A maximum conductivity was obtained by increasing the substrate temperature to 160°C. An annealing step after deposition led to a further decrease in resistivity to a value of 5.3×10-6 Ωm in a 200 nm thin film. At the same time, the optical performance could be improved. Additionally, simulations of the transmittance and reflectance spectra were carried out to compare carrier concentration and mobility determined by optical techniques with those from Hall measurements.
About the authors
Astrid Bingel studied physics at the Friedrich-Schiller University in Jena and received her diploma in 2010. Since 2008, she is a research associate at the Fraunhofer Institute for Applied Optics and Precision Engineering (IOF) in Jena, and since 2011, she works on her PhD thesis at the IOF and Institute of Applied Physics in the field of transparent conductive oxides for photovoltaic and detector applications.
Kevin Füchsel studied Physics at the Friedrich-Schiller University (FSU) in Jena and received his diploma in 2007. His diploma thesis was on ‘Low temperature deposition of indium tin oxide.’ From 2008 to 2013, he worked on his PhD thesis with the title ‘Nanostructured semiconductor-insulator-semiconductor solar cells.’ Since 2008, he is a research associate and project leader at the Fraunhofer Institute for Applied Optics and Precision Engineering (IOF), and since 2011, he is a Junior Research Group Leader at the Institute of Applied Physics/FSU. In July 2013, he became the head of the Department of Strategy, Marketing, and Coordination at the Fraunhofer IOF.
Norbert Kaiser is a Professor for Physics and Technology of Thin Films at Ernst-Abbe-Technical University Jena. He heads the Optical Thin Film Department and is the Vice Director of the Fraunhofer Institute for Applied Optics and Precision Engineering in Jena.
Andreas Tünnermann received his diploma and PhD degrees in Physics from the University of Hannover in 1988 and 1992, respectively. In 1997, he received the habilitation. He was the head of the Department of Development at the Laser Zentrum Hannover from 1992 to 1997. In the beginning of 1998, he joined the Friedrich-Schiller University in Jena, Germany, as a Professor and Director of the Institute of Applied Physics. In 2003, he was appointed as the Director of the Fraunhofer Institute for Applied Optics and Precision Engineering IOF in Jena. His main research interests include scientific and technical aspects associated with the tailoring of light. Andreas Tünnermann is author of more than 400 papers in renowned international journals. He is a sought-after expert in optics and photonics industry. He is the founder and member of the board of directors of the industry-driven cluster OptoNet Jena, one of the most dynamic regional optic clusters in Europe. His research activities on applied quantum electronics have been awarded, e.g., with the Gottfried-Wilhelm-Leibniz-Award (2005). In 2013, he became a Fellow of SPIE.
This work was financially supported by the ‘Novel-Optics’ and ‘ForMaT’ funding program of the German Federal Ministry of Education and Research, under contract number 13N9669 and 03FO3292, respectively.
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