Normal incidence germanium photodetector with an underlying silicon lateral PIN structure for short-wavelength infrared detection

In this work, we proposed a normal-incidence Ge on Si lateral PIN photodetector consisting of a lateral Si PIN diode and a Ge absorber mesa. With the Si-Ge-Si heterojunction design, the device with a 60μm² Ge mesa achieves a low dark current of 9.85nA at −1V. The responsivity reaches 0.39A/W with a thin Ge layer of 570nm. The optimized transit-time bandwidth of the device reaches 27GHz calculated with the TCAD tool.