HgCdTe APDs for low-photon number IR detection

HgCdTe avalanche photodiodes offers a new horizon for observing spatial or temporal signals containing only a few infrared (IR) photons, enabling new science, telecommunication and defence applications. A large number of HgCdTe APD based detectors have been developed at CEA LETI to address the increasing number of applications in which a faint photonic information needs to be extracted from the noise of the proximity electronics used to sample the signal. The performance of HgCdTe APDs is directly related to the multiplication process and the dark current generation in the APDs. The impact of these parameters is presented as a function of the Cd composition and geometry of the APDs. The obtained and expected performance of HgCdTe APD detectors is reported for applications ranging from very low flux observations with long observations times to high data rate telecommunications with up to single photon resolution.