Alternative Spectral Photoresponse in a p-Cu2ZnSnS4/n-GaN Heterojunction Photodiode by Modulating Applied Voltage

We report alternative visible and ultraviolet light response spectra in a p-Cu2ZnSnS4 (p-CZTS)/n-GaN heterojunction photodiode. A CZTS film was deposited on an n-GaN/sapphire substrate using a magnetron sputtering method. Current-voltage characteristic of the p-CZTS/n-GaN heterojunction photodiode showed a good rectifying behavior. The spectral response measurements indicate that the response wavelength of the photodiode can be tuned from ultraviolet to visible regions via applying zero and reverse bias. A band alignment at the interface of the p-CZTS/n-GaN heterojunction was proposed to interpret the spectral response of the device.