Transforming photodiode into avalanche photodiode: An efficient method improving the sensitivity performance of foundry-fabricated Si/Ge receiver

Avalanche photodiodes (APDs) are essential semiconductor optoelectronic devices that could effectively improve the optical receiver sensitivity due to the internal gain. Based on Si/Ge photodiodes (PDs) from standard foundry process design kits, this work demonstrates a simple tuning method to transform PDs into APDs and further improve optical receiver sensitivity by carefully increasing the bias voltage before breakdown. The tuning principle is demonstrated theoretically and experimentally. A useful method distinguishing whether a foundry-fabricated PD can be tuned to the APD is proposed via confirming if the tunneling breakdown happens before avalanche. Subsequently, based on the foundry-fabricated Si/Ge PD, the receiver sensitivity is improved by 5 dB via increasing bias voltage from 2 to 12 V under the non-return-to-zero bit rate of 10 Gbps, at the incident power of −16 dBm and gain of 3 the bit error rate is suppressed by eight orders of magnitude.