High-efficiency normal-incidence vertical p-i-n photodetectors on a germanium-on-insulator platform

In this paper, normal incidence vertical p-i-n photodetectors on a germanium-on-insulator (GOI) platform were demonstrated. The vertical p-i-n structure was realized by ion-implanting boron and arsenic at the bottom and top of the Ge layer, respectively, during the GOI fabrication. Abrupt doping profiles were verified in the transferred high-quality Ge layer. The photodetectors exhibit a dark current density of similar to 47 mA/cm(2) at -1 V and an optical responsivity of 0.39 A/W at 1550 nm, which are improved compared with state-of-the-art demonstrated GOI photodetectors. An internal quantum efficiency of similar to 97% indicates excellent carrier collection efficiency of the device. The photodetectors with mesa diameter of 60 alpha m exhibit a 3 dB bandwidth of similar to 1 GHz, which agrees well with theoretical calculations. The bandwidth is expected to improve to similar to 32 GHz with mesa diameter of 10 ae m. This work could be similarly extended to GOI platforms with other intermediate layers and potentially enrich the functional diversity of GOI for near-infrared sensing and communication integrated with Ge CMOS and mid-infrared photonics. (C) 2017 Chinese Laser Press