Pengfei Cai

80 GHz bandwidth-gain-product Ge/Si avalanche photodetector by selective Ge growth

We demonstrate selectively grown Ge/Si avalanche photodetectors with a bandwidth of 10 GHz at gain=8 at 1310 nm. The high bandwidth-gain-product of 80 GHz and Si monolithic integration capability offer great potentials for future applications.

25Gb/s normal incident Ge/Si avalanche photodiode

We developed world first 25Gb/s normal incident germanium silicon avalanche photodiode (Ge/Si APD) in a CMOS commercial foundry. The vertically illuminated Ge/Si APDs have a large 3-dB bandwidth (>18GHz) at a high gain (M=8) which is suitable for 100GBASE-ER4 application.

Reliability and non-hermetic properties of Ge/Si optoelectronic devices

Our CMOS-foundry mass-produced Ge/Si optoelectronic devices have passed the high temperature accelerated aging test, THB test and HAST test, which demonstrate satisfactory reliability and promising potential for non-hermetic applications.

Germanium on Silicon Avalanche Photodiode

Silicon photonics is considered as one of the promising technologies for high-speed optical fiber communications. Among various silicon photonic devices, germanium on silicon avalanche photodiodes (Ge/Si APDs) have attracted tremendous attention due to their the properties of high performance and low cost. The sensitivity of 10Gb/s APD reached −29.5dBm at 1550 nm with the bit error rate of 1 × 10−12 in 2015, and 25 Gb/s APD reached a highest sensitivity ever reported at about −23.5dBm at 1310 nm in 2016. Furthermore, a linear 28Gbaud APD receiver is found to have about 5dB more sensitivity than PIN solution for both multimode fiber (MMF) and single-mode fiber (SMF). Even with large defect density from lattice mismatch between Ge and Si substrate layer, Ge/Si APD devices demonstrate good reliability and pass all required qualification tests according to GR-468. In this paper, the structure, materials, process, performances, and reliability of APDs will be reviewed.