High Saturation and Broadband Uni-Traveling-Carrier Photodiode for Optical Communication System

An optimized broadband and high saturation uni-traveling-carrier photodiode is designed for optical communication system in this paper. The epitaxial layer is optimized by adopting linear doping in the absorption layer and inserting cliff layer, so as to obtain high speed and high saturation performance. According to comparing the performance of device with different thickness and doping concentration of cliff layer, the optimal epitaxial layer parameters are selected to reach the better performance. Theory and simulation study indicate that bandwidth and saturation current of the optimized device are 140 GHz and 120mA respectively, and dark current is 2 pA at 2V reverse bias.