A photodiode comprising a substrate; first semiconducting region; first contact; second region comprising an absorption region for the photons having a predetermined energy range; the second region being formed of a semiconductor having a high surface or interface recombination velocity; a third semiconducting region transparent at the predetermined photon energy range suitable for making an operative connection to a second contact; the second and third regions forming a second interface; the first and second regions forming a first interface; the second region being configured such that biasing the photodiode results in depletion of the second region from the first interface to the second interface or at least one of the absorption depth and the sum of the absorption depth and diffusion length from the second interface; the depletion resulting in the creation of an electric field whereby photogenerated carriers are collected by drift and a method of making the foregoing.