EFFECTS OF HIGH SPACE-CHARGE FIELDS ON THE RESPONSE OF MICROWAVE PHOTODETECTORS

We present simulation results, based on a one-dimensional p-i-n photod etector model, to explain the reductions in photodetector response obs erved at high optical powers. The nonlinear effects are attributed to the redistribution of the internal electric field due to space-charge effects created by the photocarriers. The corresponding modification o f the position-dependent charge velocities results in high-frequency r esponse reduction, roll-off reduction, and pulse narrowing. Electric f ield redistribution leads to two-dimensional effects, which must be in cluded for accurate modeling of milliampere photocurrents.