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

Abstract The fabrication and characterization of metal/BaTiO 3 /β‐Ga 2 O 3 solar‐blind photodetectors are reported. β‐Ga 2 O 3 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 BaTiO 3 reduces the dark current by ≈10 4 , all but eliminates illumination induced Schottky barrier lowering, and increases the UV–vis rejection ratio by a factor greater than 9 × 10 3 compared to a Schottky photodetector. It is hypothesized that the high permittivity of the dielectric overcomes the influence of self‐trapped holes in Ga 2 O 3 to reduce the peak electric field at the dielectric/metal interface, thereby eliminating the effects of Schottky barrier lowering on illuminated β‐Ga 2 O 3 photodetectors. Additionally, it is hypothesized that the increase in the UV–vis rejection ratio is caused by the “dead layer” that forms at the BaTiO 3 /Pt interface.