Enhanced UV–Vis Rejection Ratio in Metal/BaTiO3/β-Ga2O3 Solar-Blind Photodetectors

Abstract

The fabrication and characterization of metal/BaTiO3/β-Ga2O3 solar-blind photodetectors are reported. β-Ga2O3 is a promising material for solar-blind photodetectors due to its large bandgap and the availability of low defect-density melt-grown substrates. In this work, structures are introduced that employ high-permittivity dielectric/semiconductor heterojunctions to enhance the performance of a Schottky photodetector. It is shown that integrating the high-k dielectric BaTiO3 reduces the dark current by ≈104, all but eliminates illumination induced Schottky barrier lowering, and increases the UV–vis rejection ratio by a factor greater than 9 × 103 compared to a Schottky photodetector. It is hypothesized that the high permittivity of the dielectric overcomes the influence of self-trapped holes in Ga2O3 to reduce the peak electric field at the dielectric/metal interface, thereby eliminating the effects of Schottky barrier lowering on illuminated β-Ga2O3 photodetectors. Additionally, it is hypothesized that the increase in the UV–vis rejection ratio is caused by the “dead layer” that forms at the BaTiO3/Pt interface.