Wurtzite zinc-based oxynitrides as promising photovoltaic absorbers: epitaxy, band-structure engineering and heterostructures

• Applicant: Professor Dr. Marius Grundmann, since 9/2020
• Subject Area: Experimental Condensed Matter Physics ; Synthesis and Properties of Functional Materials
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 382451985

This project aims to overcome the fundamental problems of thin film solar cells, such as low cell conversion efficiency as well as technical barriers for the use of non-toxic materials. For this purpose, a new class of unconventional semiconductors with wurtzite structure will be developed by alloying ZnO with III-nitrides (AlN, GaN, InN). Bandgap engineering of such Zn-based oxynitride thin films is achievable by modulating the valence and/or conduction band edges. The substitution of both anion (N on O-site) and cation (Al, Ga and In on Zn-site) allows controllable band structures while ensuring crystallinity. As proof of concept we could reduce the bandgap of ZnO-GaN much below the values of the single compounds. The bandgap would be thereby modulated into the visible light or near-infrared regions (near 1.3 eV) for effective solar-light harvesting. The anticipated goal is tackling the critical problems of Zn-based materials in epitaxial growth and band-structure engineering for photovoltaic application.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Professor Dr. Chang Yang, Ph.D., until 9/2020