Irradiation induced degradation of high-speed response of Si p+-i-n+ photodiodes studied by pulsed laser measurements

High-speed photodetectors such as Si p⁺-i-n⁺ photodiodes are the primary components responsible for bit error rate reduction in optical links used in radiation-hard environments. In this paper, we examine degradation in the high-speed characteristics of a 1.5-GHz Si p⁺-i-n⁺ photodiode subjected to 2-MeV electron irradiation. IV, CV, and pulsed laser measurements are all performed as a function of electron fluence. Degradation in the pulsed operation is explained in terms of carrier removal effects on depletion width and base resistivity. Trapping and lifetime effects are also briefly discussed.