Development of high-speed gallium oxynitride nanowires based ultraviolet photodetectors by chemical vapour deposition technique: a facile approach

Abstract

Gallium oxynitride nanowires (GaON NWs) based ultraviolet photodetectors (UV PDs) with tunable bandgap and superior response speed is demonstrated by nitridation process in a chemical vapour deposition system. Growth rate and density of the NWs are greatly influenced by the synthesis time. With increase in growth time from 60 to 100 min, nitrogen composition in the samples increased and oxygen composition decreased, resulting in bandgap tunability from 4.63 to 4.21 eV. As an effect of bandgap tunability and dimensionality shrinkage, valence band maximum gets lifted–up due to the hybridization of O_2p and N_2p states. The fabricated GaON PDs with an appropriate nitrogen composition demonstrate significant reduction in the dark current and a faster response time of 106 µs. Oxygen vacancies get suppressed by the alteration in valence band maximum, resulting in reduced photoconductive trapping effect and enhanced response speed. When nitrogen is introduced, the probability of photoexcited charge carrier recombination increase, resulting in poor photoresponsivity. Thus, varying the nitrogen composition, bandgap tunability is achieved which suppresses charge carriers trapping in GaON. This methodology provides an alternate approach to develop high-speed ultraviolet photodetectors.