Novel X- and gamma-ray sensors based on bulk-grown silicon-germanium

In this brief, preliminary experimental results and the theoretical assessment of various compositions of bulk-grown, single-crystal silicon-germanium (SiGe) for application in X- and gamma-ray sensors, are presented. It is shown that the absorption efficiency of Si_1-xGe_x sensors is significantly superior to that of silicon sensors, even for relatively low germanium concentrations, while the bandgap narrowing should be sufficiently small not to restrict the device operation to cryogenic temperatures, as in the case of pure germanium detectors. The experimental results obtained with PIN-like devices manufactured on Si_0.95Ge_0.05 indicate suitable hole mobility, and superior detection efficiency for X-ray photons.