30 GHz GeSn photodetector on SOI substrate for 2 μm wavelength application

We report the demonstration of a normal-incidence p-i-n germanium-tin (Ge0.951Sn0.049) photodetector on silicon-on-insulator substrate for 2 mu m wavelength application. The DC and RF characteristics of the devices have been characterized. A dark current density under -1 V bias of approximately 125 mA/cm(2) is achieved at room temperature, and the optical responsivity of 14 mA/W is realized for illumination wavelength of 2 mu m under -1 V reverse bias. In addition, a 3 dB bandwidth (f(3dB)) of around 30 GHz is achieved at -3 V, which is the highest reported value among all group III-V and group IV photodetectors working in the 2 mu m wavelength range. This work illustrates that a GeSn photodetector has great prospects in 2 mu m wavelength optical communication. (C) 2021 Chinese Laser Press