High-Performance Germanium Waveguide Photodetectors on Silicon
Xiu-Li Li1,2, Zhi Liu1,2**, Lin-Zhi Peng1,2, Xiang-Quan Liu1,2, Nan Wang1,2, Yue Zhao1,2, Jun Zheng1,2, Yu-Hua Zuo1,2, Chun-Lai Xue1,2, Bu-Wen Cheng1,2
1State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 2Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049
Abstract：Germanium waveguide photodetectors with 4 μm widths and various lengths are fabricated on silicon-on-insulator substrates by selective epitaxial growth. The dependence of the germanium layer length on the responsivity and bandwidth of the photodetectors is studied. The optimal length of the germanium layer to achieve high bandwidth is found to be approximately 8 μm. For the $4 \times 8$ ${\mu}$m$^{2}$ photodetector, the dark current density is as low as 5 mA/cm$^{2}$ at $-1$ V. At a bias of $-1$ V, the 1550 nm optical responsivity is as high as 0.82 A/W. Bandwidth as high as 29 GHz is obtained at $-4$ V. Clear opened eye diagrams at 50 Gbits/s are demonstrated at 1550 nm.
2020, Vol. 37 
