High Purity CdTe and Its Application to Radiation Detectors

High quality CdTe single crystals with room-temperature resistivity of 106Ω·cm have been grown from Te solution by a travelling heater method. The optimum growth conditions are settled to be growth rate of 3 mm/day and growth temperature of around 65°C. A possibility to get much higher resistivity by controlling the Cd vapor pressure over the Te solution is suggested. A preliminary experiment of radiation detectors using 106·Ω·cm crystals has been performed. Although the experimental results are not satisfactory at present, a high counting efficiency for γ-ray superior to Ge detectors is confirmed; suggesting promising applications to environmental monitors for selfguard systems and nuclear probes for nuclear medicine.