Origin of dark counts in In _0.53 Ga _0.47As/In _0.52Al _0.48As avalanche photodiodes operated in Geiger mode

A dark count rate in InP-based single photon counting avalanche photodiodes is a limiting factor to their efficacy. The temperature dependence of the dark count rate was studied to understand its origin in In 0.53Ga 0.47As/In 0.52Al 0.48gAs separate-absorption-charge-multiplication avalanche photodiodes. The dark count rate was observed to be a very weak function of temperature in the range from 77 K to 300 K. Various mechanisms for dark count generation were considered. Simulations of band-to-band tunneling in the In 0.52Al 0.48As multiplication layer were found to agree well with the experimental temperature dependence of dark count rate at various excess biases. To reduce tunneling-induced dark counts, a suitable design change to the detector structure is proposed. © 2005 American Institute of Physics.