Simulation and modeling of p-n-p-n optical switches

A one-dimensional semiconductor device simulation program (FARDEV) with current boundary conditions is developed to study the steady-state and the transient characteristics of heterostructure four-layer p-n-p-n optical switches. Avalanche effect, radiative recombination, and band-gap discontinuities are included in the model. To demonstrate the use of the simulator, the modeling results are studied for both InP-In _0.53Ga_0.47As and Al_0.3Ga_0.7As-GaAs devices, and compared with experimental results in the latter case. The effects of optical generation and carrier lifetime on electrical characteristics of p-n-p-n switches are investigated. Simulation and experiment agree on holding current and voltage and on high-current on-state characteristics, while the limitation and simplification of the numerical model leads to discrepancy in the low-current off-state. The simulator is shown to be useful in evaluating the effects of device geometry, material parameters, avalanche mechanism, heterostructure spacing, and light generation on key switching parameters of four-layer p-n-p-n switches