Dresden 2020 – scientific programme

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DS: Fachverband Dünne Schichten

DS 37: Focus Session: Functional Metal Oxides for Novel Applications and Devices II (joint session HL/DS)

DS 37.2: Talk

Thursday, March 19, 2020, 10:00–10:15, POT 81

Optical and photocatalytic properties of gallium-zinc-oxynitrides thin films grown by molecular beam epitaxy — •Elise Sirotti, Max Kraut, Florian Pantle, and Martin Stutzmann — Walter Schottky Institut and Physics Department, Technische Universität München, Am Coulomwall 4, 85748 Garching, Germany

GaN and ZnO are two well-studied materials with favorable energy positions of their band edges with respect to the redox levels of many electro-chemical reactions. However, their large band gap limits the use for simultaneous efficient solar light absorption and photocatalytic activity. By forming an alloy of both materials, the band gap can be reduced by more than 1 eV, while the energetic position of the conduction band stays almost constant. We present the growth of GZNO thin films by means of plasma-assisted MBE on c-plane sapphire. The quality and composition of the quaternary compound have been optimized by varying the temperature, metal fluxes and nitrogen-to-oxygen ratio during deposition. We performed photo-thermal deflection spectroscopy, valence band XPS and EDX measurements to investigate the influence of the composition on the electronic properties. As a result, the influence of the different components on the energetic positions of the conduction band and valence band has been clarified. With electrochemical measurements, we gain insights into the photo-catalytic activity and stability of the thin films. The high flexibility gained by MBE growth allows us to acquire additional knowledge about the fundamental principles of the band gap narrowing process.