Tl-based wide gap semiconductor materials for x-ray and gamma ray detection

The optical and electronic properties of Tl-chalcogenide, wide gap semiconductors, TlGaSe2, Tl6I4Se, and Tl2Au4S3 for x-ray and γ ray detection were characterized. The semiconductor crystals are grown by the modified Bridgman method. The optical absorption and band gap energy of the materials were determined from UV-Vis-near IR transmission and reflection spectra. The mobility-lifetime products were measured. For Tl6I4Se the values were comparable to those of CdZnTe. We measured room temperature detector response to x-ray and γ ray radiations. Under 57Co radiation, Tl6I4Se has a well-resolved spectral response and peak FWHM comparable to those of Cd0.9Zn0.1Te.