Theoretical Study on the Role of Gating and Photoconduction on Ga 2 O 3 Phototransistors

Gallium oxide (Ga 2 O 3 ) phototransistors with low dark current and high ON-OFF ratio have been attracting considerable attention for UV-C light detection applications.However, the joint influence of photoconduction and gating on their photoresponse behaviors makes the photodetection mechanism experimentally ambiguous.Herein, a theoretical study on Ga 2 O 3 phototransistors is performed with technology computer-aided design (TCAD) Silvaco software to reveal the role of gate bias and external UV-C light illumination on their electrical characteristics.The analyses on the transfer curves before and after 250-nm light illumination figure out that the responsivity increases and then decreases with the gate bias, and the gate bias required to achieve the maximum responsivity increases with Ga 2 O 3 thickness.Interestingly, under weak light irradiation, the current density of Ga 2 O 3 phototransistors is found to be obviously enhanced by the gate bias owing to the effective separation of photo-generated electron-hole pairs.However, this gating effect is weakened upon strong UV-C light illumination.Our theoretical work clarifies the synergism and competition relationships between photoconduction and gating effects and offers a reference for the design of high-performance Ga 2 O 3 phototransistors.