Silicon photonics technology has drawn significant interest due to its potential for compact and high-performance photonic integrated circuits. The Ge- or III–V material-based avalanche photodiodes integrated on silicon photonics provide ideal high sensitivity optical receivers for telecommunication wavelengths. Herein, the last advances of monolithic and heterogeneous avalanche photodiodes on silicon are reviewed, including different device structures and semiconductor systems.

We demonstrate low-voltage waveguide silicon-germanium avalanche photodiodes (APDs) integrated with distributed Bragg reflectors (DBRs). The internal quantum efficiency is improved from 60% to 90% at 1550 nm assisted with DBRs while still achieving a 25 GHz bandwidth. A low breakdown voltage of 10 V and a gain bandwidth product of near 500 GHz are obtained. APDs with DBRs at a data rate of 64 Gb/s pulse amplitude modulation with four levels (PAM4) show a 30%–40% increase in optical modulation amplitude (OMA) compared to APDs with no DBR. A sensitivity of around ?13dBm at a data rate of 64 Gb/s PAM4 and a bit error rate of 2.4×10?4 is realized for APDs with DBRs, which improves the sensitivity by ～2dB compared to APDs with no DBR.