State of the art of wide-bandgap semiconductor nuclear radiation detectors

The leading materials which operate as room temperature nuclear radiation detectors are HgI2, CdTe, and Cd1-xZnxTe (0.05 > x > 0.25). However, additional materials have also been developed, such as semi-insulating GaAs and PbI2. A comparison of the charge transport properties of all these materials will be made, followed by a discussion of each of the materials separately. Crystal growth methods of spectrometer-grade materials will be mentioned, and defects which Limit their performance will be discussed. Nuclear spectra measurements with detectors fabricated from these materials, for low X-ray energies as well as for high-energy gamma-rays, will be shown. Polarization effects which occur in some detectors such as HgI2 will also be discussed. Correlation between crystalline perfection and detector performance will be shown. Results of quantitative chemical analysis of various detector materials and problems encountered in determining accurate values of x in Cd1-xZnxTe and its homogeneity in the bulk will be presented. Finally, the present state of the art and developments for the near future will be discussed.