The objectives of this activity are to design, manufacture and characterise a large-format MCT APD array optimised for low dark current and low photon-flux detection.

In recent years, the traditional MCT (Mercury Cadmium Telluride) technology for near-infrared (NIR) sensing has been developed further to manufacture APD (Avalanche Photo-Diode) arrays, which enables sub-electron readout noise measurements. This technology is now routinely used for wave-front sensing on ground-based telescopes using small format devices. Further effort to increase the size of NIR APD sensors as well as improving the MCT material properties (e.g. lower dark current) is needed such that they can be used for future ground and space-based scientific instrumentation. The IRT instrument (Infra-Red Telescope), onboard the ESA Cosmic Vision M5 candidate mission THESEUS, would greatly benefit from such a development as its scientific performance will be readout noise limited using the standard MCT technology. The goal of this activity is to develop a 2k x 2k MCT APD array with a radiation-hard ROIC and dark current performance compatible with imaging for Astronomy while preserving sub-electron readout noise capability and high quantum efficiency in the NIR and - as a goal - in the visible wavelength ranges.