THE OPTICAL TRANSFER FUNCTION OF SILICON SOLAR CELLS: THEORY AND EXPERIMENT

Abstract

Silicon solar cells have traditionally been used for conversion of direct sunlight to energy. These cells can also be used as low rate optical detectors. The internal resistances and capacitances, however, limit the usable bandwidth. Under forward bias conditions, diodes exhibit, in addition to the depletion layer capacitance, a diffusion capacitance caused by the rearrangement of minority carriers. A similar process occurs in solar cells when photons are absorbed and electron-hole pairs are produced. This paper presents a method successfully used by the authors to determine this unknown term as a function of background illumination.