Displacement damage in Hydrogenated Amorphous Silicon p-i-n diodes and charge selective contacts detectors.

Hydrogenated amorphous silicon is a well known detector material for its radiation resistance. This study concern 10 µm thickness, p-i-n and charge selective contacts planar diode detectors which were irradiated with neutrons at two fluence values: 10¹⁶ n_eq/cm² and 5 x 10¹⁶ n_eq/cm². In order to evaluate their radiation resistance, detector leakage current and response to X-ray photons have been measured. The effect of annealing for performance recovery at 100°C for 12 and 24 hours has also been studied. The results for the 10¹⁶ n_eq/cm² irradiation show a factor 2 increase in leakage current that is completely recovered after annealing for p-i-n devices while charge selective contacts devices show an overall decrease of the leakage current at the end of the annealing process compared to the measurement before the irradiation. X-ray dosimetric sensitivity degrades, for this fluence, at the end of irradiation but partially recovers for charge selective contacts devices and increases for p-i-n devices at the end of the annealing process. Concerning the 5 x 10¹⁶ n_eq/cm² irradiation test (for p-i-n structures only), due to the activation occurred during the irradiation phase, the results were taken after 146 days of storage around 0° C when a self-annealing effect may have occurred. Nevertheless the results shows a degradation in leakage current and x-ray sensitivity which changes very little after annealing.