Sputtered Sr x NbO3 as a UV-Transparent Conducting Film

• Published in: ACS applied materials & interfaces 2020-07, Vol.12 (27), p.30520-30529
• Main Authors: Roth, Joseph, Paul, Arpita, Goldner, Nathan, Pogrebnyakov, Alexej, Agueda, Kleyser, Birol, Turan, Alem, Nasim, Engel-Herbert, Roman
• Format: Article
• Language: English
• Subjects: Functional Inorganic Materials and Devices
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.0c04854

Expanding the application space of transparent electrodes toward the ultraviolet range has been found challenging when utilizing the conventional approach to degenerately dope semiconductors with band gaps larger than ZnO or In2O3. Here, it is shown that the correlated metal Sr x NbO3 with x < 1 is ideally suited as a UV-transparent electrode material, enabling UV light-emitting diodes for a wide range of applications from water disinfection to polymer curing. It is demonstrated that Sr x NbO3 thin films can be grown by radio frequency (RF) sputtering and that they remain in the perovskite phase despite a sizeable Sr deficiency. The electrical and optical properties are characterized and compared to those of commonly used indium tin oxide (ITO) and Sn-doped Ga2O3 transparent conductor standards. Sr x NbO3 films were found to have sheet resistances as low as 30 Ω sq–1 with optical transmission at a wavelength of 280 nm up to 86%, marking a two-order-of-magnitude increase over the performance of traditional UV-transparent conductors. The compatibility of Sr x NbO3 with a physical vapor deposition technique that is widely employed in the transparent conductor coating industry along with the robustness of the highly electrically conducting and optically transparent perovskite phase makes it an ideal transparent electrode for applications in the UV spectrum.