The photon-counting performance of commercially available InGaAs/InP avalan
che photodiodes operated in Geiger mode was investigated at temperatures be
tween 77 and 260 K. In particular, their noise equivalent power was measure
d to be 4 x 10(-17) WHz(-1/2) at 77 K. The implications of these results in
the context of a quantum cryptography application are discussed.