Growth and characterization of CdTe single crystals for radiation detectors

To improve the productivity of CdTe radiation detectors, the crystal growth by traveling heater method (THM) as well as the quality of the fabricated detectors were investigated. In the THM growth, optimization of the solvent volume was found to be essential because it affects the shape of the growth interface. The use of the slightly tilted seed from 〈1 1 1〉B was also effective to limit the generation of twins having different directions. Single-crystal (1 1 1) wafers, larger than 30×30 mm2 were successfully obtained from a grown crystal of 50 mm diameter. Pt/CdTe/Pt detectors of dimensions 4×4×2 mm3, fabricated from the whole crystal ingot, showed an energy resolution (FWHM of 122 keV peak from a 57Co source) between 6% and 8%. Similarly, Pt/CdTe/In detectors of dimensions 2×2×0.5 mm3 showed a resolution better than 3%. These characteristics encourage the practical applications of various types of CdTe detectors.