Electrical performance of laser damaged silicon photodiodes

Laser induced electrical parameter degradation and morphological damage have been observed in silicon photodiodes. The samples were RCA reach-through avalanche photodiodes and EG&G PIN photodiodes. The laser source was a 1064-nm Q-switched Nd: YAG laser (10-Hz, 10-ns pulses with a 300-microm spot radius). Reverse saturation current, noise current, breakdown voltage, junction capacitance, and surface morphology were monitored for permanent laser induced change. The current characteristics were clearly the most sensitive electrical parameters; however, the electrical performance was generally insensitive to severe surface morphological damage. The damage behavior indicated that the electrical degradation in photodiodes may be modeled by the introduction of defects into the depletion region by deep melting transients.