Performance characteristics of avalanche photodiodes

The conventional McIntyre carrier multiplication theory for avalanche photodiodes, APDs, does not adequately describe the experimental results obtained from APDs with thin multiplication regions. Both gain and excess noise factor have reduced values in thin multiplication regions, as confirmed by the reported experimental results, which is not predicted by conventional models. In this paper a new analytical model for avalanche multiplication, based on both the conventional local field theory and the new dead space history-dependent theory, is proposed. The proposed model is used to calculate the performance parameters of GaAs, Al_0.2Ga_0.8As, and Al_0.3Ga_0.7As APDs with thin multiplication regions of various widths, namely, gain and excess noise factor. Simulation results using the proposed model show very good agreement with reported experimental results, much better than the conventional theory, particularly in devices with thin multiplication regions.