High-Gain Ge/Si Avalanche Photodetector Enhanced by Distributed Structure

We demonstrate a Ge/Si distributed avalanche photodetector (APD). By implementing 4 -stage and 8 -stage APD schemes, the avalanche gain is enhanced from 11 to 30 and 55, respectively. Furthermore, the corresponding gain-bandwidth product is improved from 102 GHz to 233 GHz and 577 GHz.