64 Gbps PAM4 Si-Ge Waveguide Avalanche Photodiodes With Excellent Temperature Stability

A Si-Ge waveguide avalanche photodiode with extremely high temperature stability is demonstrated. The breakdown voltage increases ∼4.2 mV/°C, bandwidth reduces ∼0.09%/°C, and gain-bandwidth product reduces ∼0.24%/°C with temperature increased from 30 °C to 90 °C. Additionally, it maintains superior performance with low breakdown voltage of ∼10 V, high multiplication gain of >15, high bandwidth of ∼24.6 GHz, high gain-bandwidth product of >240 GHz, high internal quantum efficiency of ∼100%, and clear eye diagrams with 64 Gbps PAM4 modulation at 90 °C.