Study of silicon carbide for X-ray detection and spectroscopy

This work presents an analysis of silicon carbide (SiC) as semiconductor for the realization of detectors for soft X-rays (<20 keV). On the basis of experimental data on prototype SiC junctions, the performance in X-ray spectroscopy using planar diode and drift detectors in SiC have been estimated in a wide range of operating temperature (up to 150°C). It has been derived that, due to their extremely low reverse current density (4.7 pA/cm² at 300 K and 17 pA/cm² at 340 K and at electric field of 100 kV/cm), SiC detectors can potentially reach superior performance with respect to all the other semiconductors presently employed at or above room temperature. In particular, a comparative theoretical analysis, based on experimental data on state-of-the-art silicon and SiC junctions, shows that SiC detectors with areas larger than 1 mm² have the potentiality to offer higher energy resolution when operating at temperature above 25°C. An energy resolution of about 700 and 1300 eV FWHM have been estimated for 1 mm² and 10 mm² SiC pad detectors operating at 100°C with a silicon front-end FET. The contribution of a standard silicon front-end electronics on the system performance has been analyzed. The open issues in SiC technology for X-ray detector development are highlighted.