Lateral incidence Ge-on-Si photodetector with high saturation characteristics

Abstract

This paper presents a novel lateral incidence Ge-on-Si photodetector designed to utilize laterally incident light, achieving a uniform light field distribution within the germanium absorption region. The LI-PD features a germanium layer whose length is greater in the direction perpendicular to the incident light than in the parallel direction. Additionally, residual light is reabsorbed through reflection from the DBR, and the electrode design has been optimized to minimize light absorption. Despite a relatively small active region, the photodetector demonstrates a saturated photocurrent of 9.79 mA and a bandwidth of 22.62 GHz at an incident light power of 20 mW, compared to 7.23 mA and 9.39 GHz in conventional photodetectors. Moreover, at low optical power (0.5 mW), when the frequency exceeds 11.25 GHz, the responsivity of this device surpasses that of traditional structures.