Drift-diffusion model for reach-through avalanche photodiodes

A 1-D drift-diffusion model is developed for reach-through avalanche photod iodes. Based on this model an equivalent circuit is suggested for these dev ices. The equivalent circuit is suitable for simulating the device in circu it simulation packages such as PSpice. The model is validated by simulating an actual reach-through silicon avalanche photodiode in the steady state a nd the transient conditions. Some of the simulation results are compared to the manufacturer data by estimating the device parameters. This model is a lso used to investigate the effect of the device microstructure on its perf ormance. For a certain operating bias voltage and wavelength, it is found t hat the multiplication width has a critical value for defining the device s tability. The absorption width defines the wavelength for peak responsivity , which suggests a structure enhancement for IR detection. Also the effect of varying the doping concentration is studied. (C) 2001 Society of Photo-O ptical Instrumentation Engineers.