Comparison of the performance of a-Si:H sensors designed with different contacts configurations

The HASPIDE project of INFN exploits hydrogenated amorphous silicon (a-Si:H) as a sensitive material for innovative detectors, mainly focused on dosimetry both for standard and FLASH radiotherapy, but also fo other applications. The detector, deposited on a thin and flexible substrate of polyimide, has been developed with different contacts configurations during past years, giving rise to the necessity to compare them in order to determine which configuration is best, for a specific application. In particular, three types of contacts are under exam in this work: the first one is a classical n-i-p junction, where a thick layer of intrinsic a-Si:H material is sandwiched between n- and p-doped layers of hydrogenated amorphous silicon; the second configuration is a charge-selective contacts device (CSC), where the doped regions are replaced with metal oxides which selectively enhance the mobility of one charge-carrier, blocking the other and the last one is the hybrid type, in which the intrinsic region is coupled with a n-doped layer on the bottom and a hole selective metal oxide on the top. This work aims to give a comparison in the performance of three devices differing only in the contact configuration, in terms of dark current analysis and sensitivity to X-ray beams, so that the characteristics of each one can be analyzed and exploited.