Degradation of responsivity for photodiodes under intense laser irradiation

Experiments of photodiodes irradiated by laser at various energy densities are performed in this study. The laser-induced changes in photocurrent and dark current are monitored, the degradation process of responsivity as a function of the laser energy density is obtained. Morphological examinations were done with a scanning electron microscope (SEM), and damaged depth was performed using a step profiler. The results indicate that the relative responsivity of photodiodes for He Ne probe beam gradually reduced with the increase of intense laser energy density. The mechanism of various degradation of responsivity was analyzed. The obvious decrease of responsivity mainly contributes to an increase in the surface recombination velocity caused by defects and thermal breakdown of PN junction. The results were significant for the study of interaction laser with material.