Characterization and Modelling of High Speed Ge Photodetectors Reliability

Performance degradations of Silicon Photonics (SP) high speed photodetector represent a major issue for the reliability of these devices. An explanation of these degradations is presented based on both electrical characterization and device modelling. The observed degradations of both dark current and responsivity can indeed be modeled by a single carrier lifetime degradation, attributed to an increase of the surface recombination rate, impacting an unexpected large contribution of diffusion in the photocurrent. The results obtained with this model are experimentally confirmed by extracting the activation energy of the dark current, before and after stress. The improved physical understanding of the degradation is expected to lead to shorter test protocols for SP devices.