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Role of self-trapped holes in the photoconductive gain of β -gallium oxide Schottky diodes

2016; American Institute of Physics; Volume: 119; Issue: 10 Linguagem: Inglês

10.1063/1.4943261

1520-8850

Andrew Armstrong, Mary H. Crawford, Asanka Jayawardena, A. C. Ahyi, Sarit Dhar,

Advanced Photocatalysis Techniques

Solar-blind photodetection and photoconductive gain >50 corresponding to a responsivity >8 A/W were observed for β-Ga2O3 Schottky photodiodes. The origin of photoconductive gain was investigated. Current-voltage characteristics of the diodes did not indicate avalanche breakdown, which excludes carrier multiplication by impact ionization as the source for gain. However, photocapacitance measurements indicated a mechanism for hole localization for above-band gap illumination, suggesting self-trapped hole formation. Comparison of photoconductivity and photocapacitance spectra indicated that self-trapped hole formation coincides with the strong photoconductive gain. It is concluded that self-trapped hole formation near the Schottky diode lowers the effective Schottky barrier in reverse bias, producing photoconductive gain. Ascribing photoconductive gain to an inherent property like self-trapping of holes can explain the operation of a variety of β-Ga2O3 photodetectors.