In a prior work analytical estimates of the saturation currents of ideal three-dimensional diodes were obtained. It was illustrated that the analytical forms obtained could also be used to provide an estimate of the photocurrents produced by these diodes when they are flood illuminated. This paper discusses the accuracy of the estimates obtained, the estimates from the point-of-view of experimental verification and extends the analysis to consider the influence of nonideal surfaces/contacts and optical masking. The results indicate that bulk generation saturation currents in photodiodes in three-dimensional structures can greatly exceed the saturation currents of planar diodes with the same junction area, but are less than indicated by thermal generation within a diffusion length of the junction. Nonideal surfaces/contacts tend to increase an already large saturation current influence, but not to the extent of their influence on planar diode behavior.
Edwin B. Champagne,
"Saturation Currents And Photocurrents In Three-Dimensional Photodiodes", Proc. SPIE 0510, Infrared Technology X, (21 January 1985); doi: 10.1117/12.945026; https://doi.org/10.1117/12.945026