Computer calculations of the photoresponse of a diffused silicon pn-junction using the Gummel-de-Mari algorithm

Computer calculations based on the Gummel-de Mari (1964, 1968) algorithm were used to study the photoresponse of a diffused silicon p-n junction. Parameters relevant to the fabrication of these diodes were varied, such as substrate doping, diffusion time (junction depth) and carrier lifetime. The wavelength dependence of the response as a biased photodetector was studied along with the junction operation in the photovoltaic mode (solar cell application) using an approximate solar spectrum. It is shown that the use of the computer program gives useful insight into the operation of p-n junctions with photoexcitation, both in the reverse-biased photodetector mode of operation and in the forward-biased (photovoltaic solar cell) mode, thereby providing a means for further optimization. An important result is the information obtained on carrier loss at the contacts.