Prospect for energy resolving X-ray imaging with compound semiconductor pixel detectors

Some of the latest results of the research activity on compound semiconductor pixel detectors are presented and discussed. In particular, this article will present the most recent achievements obtained with Gallium Arsenide (GaAs) and Silicon Carbide (SiC) detectors, which are showing outstanding performance in the compound semiconductor detectors scenario. Devices with room-temperature leakage current densities comparable with or much better than silicon devices (1 nA/cm2 for GaAs and 1 pA/cm2 for SiC) have been realized, allowing high-resolution X-ray spectroscopy. GaAs pixel arrays for X-ray spectroscopic imaging with areas up to 1 cm2 have been produced. The equivalent noise energies around 240-310 eV FWHM at room temperature, as demonstrated both with GaAs and SiC pixel detectors, are not limited by the detectors but by the noise of the front-end electronics. At -30 deg C, 163 eV FWHM has been reached with GaAs. SiC pixel detectors with less than 1 electron r.m.s. of electronic noise at room temperature are presented. The real limiting factors of GaAs and SiC X-ray detectors are identified and the directions for the research activities necessary for further improvements are indicated