High performance InGaN/GaN visible-light field effect phototransistor using polarization induced virtual photogate

Abstract

Visible-light field effect phototransistors (FEPTs) with high detectivity and high speed are fabricated using a polarization induced photogate in a simple In0.15Ga0.85N/GaN heterostructure, where the pure polarization electric field acts as a virtual photogate of the FEPT and the total In0.15Ga0.85N layer plays the roles of absorber and channel. Experimental results show that the polarization electric field from high quality pseudo-crystalline InGaN/GaN structure can fully deplete the channel layer and leads to an ultra-low dark current. Furthermore, the channel conductivity can be significantly promoted with visible-light illumination. Therefore, the FEPT achieves a high visible-light gain of 6.0 × 104 and a superhigh shot noise limited specific detectivity of 1.5 × 1016 Jones, as well as a high speed with 15 ns/160 ns rise/fall time. The results not only present huge potential in visible-light photodetection, but also provide an insight into the application of polarization effects in wide bandgap semiconductors.