Degradation and Recovery Kinetics Study of Vertical and Lateral Ge-on-Si Photodetectors

In the context of Silicon Photonics technology's rapid growth, we present a comparative study of the degradation and relaxation kinetics under constant voltage stress across various Ge-on-Si p-i-n waveguide photodiode configurations. By combining calibrated Technology Computer-Aided Design (TCAD) simulations with experimental data, defect generation, charge injection and trap annealing mechanisms occurring in bulk Ge, and around Ge/Si and Ge/SiO
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interfaces were revealed. The intricate interplay between device geometry, electric fields, hot carrier effects, and energy band alignments dictates the dominant mechanism and, consequently, shapes the overall changes of dark current over time. Our study paves the way for effective design strategies aiming at the early detection of potential degradation issues and enhancing the reliability of integrated germanium photodiodes.