Nonlinear saturation behaviors of high-speed p-i-n photodetectors

We present numerical simulations of the ultrafast transport dynamics in an ultrahigh-speed double-heterostructure p-i-n photodetector, Nonlinear satur ation behaviors under high field and high power illumination are investigat ed with the external circuit response considered. Damping constants and dif fusion constants are both treated as electric-field- and carrier-concentrat ion-dependent in our model in order to take into account the effect of carr ier scattering, We have also considered the carrier trapping at the heteros tructure interfaces for the first time. Besides the drift-induced space cha rge screening effect, we find that saturation of external circuit and carri er-trapping-induced screening effect are also the dominant mechanisms contr ibuted to the nonlinear bandwidth reduction under high power illumination. On the other hand, previously reported plasma oscillations are found to be greatly suppressed by including strong carrier diffusion effect in the mode l.