GaN MSM structure UV photodetector detector based on nonplanar Si substrate and its performance optimization

Abstract

Silicon (Si) based gallium nitride (GaN) possesses great development potential in fabricating integrated photodetectors. Nevertheless, the large lattice and thermal mismatch between Si and GaN usually brings about high-density dislocations and other line defects, which as a whole will seriously affect the responsiveness, working stability and service life of Si-based GaN (GaN/Si) devices. In this paper, we report that a GaN/Si ultraviolet photodetector (UV PD) with a metal-semiconductor-metal structure was prepared, using silicon nanoporous pillar array (Si-NPA) as nonplanar substrates. It will be shown that high-quality GaN/Si can be prepared and further improved by subsequent annealing treatment, by means of a three-dimensional stress release process brought about by using patterned Si substrates. Under a bias voltage of 1 V, the responsivity, specific detectivity, external quantum efficiency and rise/decay time of the detector were 71.4 mA·W−1, 7.1 × 108 Jones, 24.3% and 0.2/7.6 s, respectively. The results demonstrate that growing GaN on patterned Si substrates might be an effect route for constructing high-performance GaN/Si UV PDs.