Dark current and 1/f noise in forward biased InAs photodiodes

Dark current and low-frequency noise have been studied in forward biased InAs photodiodes within the temperature range 77…290 K. Photodiodes were fabricated by diffusion of Cd into n-InAs single crystal substrates. It has been shown that, at the temperatures >130 K, the forward current is defined by recombination of charge carriers with participation of deep states in the middle of band gap. At these temperatures, a correlation is found between forward current and 1/f noise. At lower temperatures, the forward current and noise have been analyzed within the model of inhomogeneous p-n junction caused by dislocations in the depletion region. The experimental evidence has been obtained that multiple carrier tunneling is the main transport mechanism at low temperatures, which leads to an increase in low-frequency noise.