Growth of Cd_0.9Zn_0.1Te single crystals for room temperature gamma radiation detection

Room temperature semiconductor gamma radiation detectors based on Cd_0.9Zn_0.1Te (CZT) occupy an important niche between the cryogenically cooled HpGe detectors and scintillation detectors. CZT detectors exhibit a resolution of about 1% or lower for the 662 keV ¹³⁷Cs gamma line. Gamma ray spectrometers are an important tool in checking the proliferation of nuclear weapons. In addition to nuclear non-proliferation, nuclear medicine, computed tomography and non-destructive testing are other applications where high performance detectors are required. In THM the molten solvent (excess Te) is made to migrate through a solid source material (CZT) by the slow movement of the charge relative to the heater. In this process, the dissolution of feed material occurs at the advancing (hotter) liquid-solid interface and the crystallization of the feed material occurs at the receding (cooler) liquid-solid interface. The ingots of 20 mm diameter and 60 mm length were grown. Single crystallinity of the grown crystals is confirmed by Laue diffraction. X-ray rocking curve analysis yielded FWHM of 360 arc sec. The band gap value (1.54 eV) is calculated from NIR transmission spectra. The resistivity of the grown crystal is ~ 10⁹ ohm-cm from I-V measurements