Theory and Modelling of High-Field Carrier Transport in High-Speed Photodetectors

The authors present analytical microscopic theory and numerical simulation of high-field hot-electron effects in highspeed p-i-n and uni-travelling carrier (UTC) photodetectors (PDs), using both the drift-diffusion (DD) and hydrodynamic (HD) models for steady-state and transient regimes. It is shown that the current models of drift mobility in DD transport are not applicable for strongly inhomogeneous systems with built-in fields. A new DD mobility model is suggested. Comparative analysis of DD and HD modeling results is carried out and it is shown that the HD model adequately describes operation of high-speed PDs excited by short sub-picosecond optical pulses.