Light-Driven WSe2-ZnO Junction Field-Effect Transistors for High-Performance Photodetection

Assembling nanomaterials into hybrid structures provides a promising and flexible route to reach ultrahigh responsivity by introducing a trap-assisted gain (G) mechanism. However, the high-gain photodetectors benefitting from long carrier lifetime often possess slow response time (t) due to the inherent G-t tradeoff. Here, a light-driven junction field-effect transistor (LJFET), consisting of an n-type ZnO belt as the channel material and a p-type WSe2 nanosheet as a photoactive gate material, to break the G-t tradeoff through decoupling the gain from carrier lifetime is reported. The photoactive gate material WSe2 under illumination enables a conductive path for externally applied voltage, which modulates the depletion region within the ZnO channel efficiently. The gain and response time are separately determined by the field effect modulation and the switching speed of LJFET. As a result, a high responsivity of 4.83 x 10(3) A W-1 with a gain of approximate to 10(4) and a rapid response time of approximate to 10 mu s are obtained simultaneously. The LJFET architecture offers a new approach to realize high-gain and fast-response photodetectors without the G-t tradeoff.