Resonant cavity germanium photodetector via stacked single-crystalline nanomembranes

In this paper, the authors report resonant cavity (RC) metal-semiconductor-metal (MSM) germanium nanomembrane (Ge NM) photodetectors via transfer printing. The dislocation-free Ge NM layer was transferred onto an ultrathin Si NM/SiO2 distributed Bragg reflector. As a result, a low dark current density of 1 × 10−9 A/μm2 and a quantum efficiency of 17.3% at 1.55 μm, which is twice larger than the quantum efficiency without a bottom mirror, were measured from the transferred RC MSM Ge photodetector. The enhancement of the quantum efficiency is verified by simulation.