A Time-domain Carrier Generation Rate Model for Optoelectronic Device Simulations

The nonlinear interactions between electromagnetic fields and carriers in optoelectronic devices call for a multiphysics simulation approach to be carried out in the time domain. The widely used Poynting vector-based carrier generation rate model leads to an unphysical divergent solution when strong low-frequency fields are generated by moving carriers. This work proposes a material absorption-based carrier generation rate model for time-domain simulation of optoelectronic devices. The optoelectronic material is described by a Lorentz dispersion model with poles in the optical frequency range and negligible absorption at lower frequencies. The instantaneous optical absorption, which is computed from the polarization current density, is used to obtain the generation rate. Numerical examples show that the proposed method is more accurate than the Poynting vector-based model and is stable even when the generated lower-frequency fields are strong.