Starting with highly purified feed material, single crystals of semiinsulating CdTe were grown by the use of the traveling heater method, without external chemical compensation. Evaluation of the crystals by the use of electrical and optical measurements showed decisive improvements in quality. Nuclear radiation detectors prepared by the use of this material resulted in an energy resolution (FWHM), at room temperature, of 4.6 and 8.5 keV for &ggr; rays at energies of 122 and 662 keV, respectively. The energy resolution at 122 keV decreased to 3.8 keV at a temperature of −30°C. No polarization effect was observed.