Photoresponse of few-layered GaS0.3Se0.7 alloy transistors

Efficient bandgap engineering is of great significance for developing high-performance optoelectronic devices. Few-layered GaS photodetectors have shown promising photoresponsivity only with the spectral window in the ultraviolet (UV) region. It is necessary to explore alloying GaS and GaSe to improve the performance of devices. Here, the field-effect transistors (FETs) based on ultrathin layer GaS0.3Se0.7 are designed and fabricated. The results show that few-layered GaS0.3Se0.7 FETs exhibit typical p-type semiconductor properties. Our study shows the photoresponse of few-layered GaS0.3Se0.7 FETs (on SiO2/Si) at 405 nm in visible light region is 231 mA/W with an ON/OFF ratio of 140, at a power density of 16.5 mW/cm(2), an external quantum efficiency of 71%, and a detection rate of 4.08 x 10(11) Jones. The results provide a method to improve the electrical properties of optoelectronic devices based on a 2D material alloy.