Abstract: Numerical simulation using a variable finite difference technique has been performed to study the transient behavior of extrinsic photoconductors and the steady state behavior of blocked impurity band detectors. Comprehensive modeling of transient behavior shows that carrier sweep-out causes a two component response to illumination changes in extrinsic photoconductors. Simulations for large signals on low photon backgrounds indicate that the background flux plays an important role in transient response, even when the signal is many orders of magnitude larger than background. Modeling of blocked impurity band detectors illustrates the field variations that determine device performance. When blocking layer doping exceeds a critical value, a field gradient develops at the blocker/absorber interface due to the ionization of neutral acceptors. In practice, this would reduce the efficiency of transport in the blocking layer and decrease device responsivity. !8
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