Depletion-Mode A-GaOx Solar-Blind Phototransistors for Optoelectronic Mixed Logic Gate Circuit and Solar-Blind Imaging

Abstract

Phototransistors based on Ga₂O₃ are widely used in civil or military applications as a three-terminal device with solar-blind characteristics. This study constructed amorphous gallium oxide (a-GaO_x) thin film transistor (TFT)-based solar-blind photodetectors and explored the effect of the oxygen partial pressure on films and devices. It had been found that there is a strong correlation between oxygen partial pressure and photodetector properties. Decreasing oxygen partial pressure increases the carrier concentration, resulting in a shift of device threshold voltage (V_th) from 15 V to −5 V, thereby causing the device to transition from enhancement mode to depletion mode. And the a-GaO_x TFT-based solar-blind photodetector in depletion mode has an ultrahigh performance, with a responsivity (R) of 1038 A/W and an I_on/I_off ratio of 10⁷ at a gate voltage (V_G) of −5 V and a responsivity of 2100 A/W at a V_G of 100 V. And the reconfigurable basic logic functions (“AND”/“OR”) have been achieved. Furthermore, the imaging is realized by assembling a-GaO_x thin film transistor-based solar-blind photodetector arrays (a-GaO_x TFT-PDAs).