The response of small photovoltaic detectors to uniform radiation

The short-circuit photocurrent of a small photodiode under uniform illumination is discussed for the case of diffusion length larger than the absorption depth. Lateral response, resulting from carrier diffusion in the substrate near the photodiode, is taken into account. Numerical results of a two-dimensional analysis are presented and compared to one-dimensional approximations. Effects of various parameters, such as surface recombination velocity and excess carrier lifetime on the lateral response are discussed.