Silicon–germanium avalanche photodiodes with direct control of electric field in charge multiplication region

Abstract

A CMOS-compatible avalanche photodiode (APD) with high speed and high sensitivity is a critical component of a low-cost, high-data-rate, and energy-efficient optical communication link. A novel waveguide-coupled silicon–germanium APD detector with three electric terminals was demonstrated with breakdown voltage of −6  V, bandwidth of 18.9 GHz, DC photocurrent gain of 15, open-eye diagram at a data rate of 35 Gb/s, and sensitivity of −11.4  dBm at a data rate of 25 Gb/s. This three-terminal APD allows high-yield fabrication in the standard CMOS process and provides robust high-sensitivity operation under small voltage supply.