Numerical Drift-Diffusion Simulation of GaAs p-i-n and Schottky-Barrier Photodiodes for High-Speed A III B V On-Chip Optical Interconnections

摘要

In this paper, we consider the problem of the research and development of high-speed semiconductor photodetectors suitable for operation as parts of on-chip optical interconnections together with the high-speed laser modulators based on the A III B V nanoheterostructures. This research is aimed at the development of the models and modelling aids designed for the simulation of carrier transport and accumulation processes taking place in on-chip photosensitive devices during the detection of subpicosecond laser pulses. Another aim of the paper is to apply the aforementioned aids for the investigation of GaAs p-i-n and Schottky-barrier photodiodes. We propose the non-stationary drift-diffusion models, an original numerical simulation technique and the applied software allowing one to simulate the photosensitive devices with different electrophysical, constructive and technological parameters. We have taken into account different kinds of carrier generation and recombination processes, the effects of electron intervalley transition and carrier drift velocity saturation in order to improve the simulation results’ adequacy. We have concluded that the influence of these effects on the performance of photodetectors for on-chip optical interconnections is significant. The response time of GaAs p-i-n and Schottky-barrier photodiodes calculated taking into account the drift velocity dependence on electric field intensity is insufficient for the adequate detection of subpicosecond laser pulses. According to the simulation results, it is reasonable to develop the methods aimed at the increase in the drift velocity of charge carriers in the photodetector active region by means of built-in electric field reduction.