Preparation and properties of hemispherical CdMnTe nuclear radiation detectors

Abstract

As a new generation of semiconductor materials, cadmium manganese telluride (CdMnTe) is a candidate material for nuclear radiation detection in environmental monitoring and industrial nondestructive testing. In general, a planar detector with symmetrical electrodes decreases energy resolution because of incomplete hole collection. To increase energy resolution, a hemispherical detector was designed with a volume of 4 × 4 × 2 cm3. First, the infrared transmittance of the wafers was investigated, and the best wafer was chosen. Second, the planar and hemispherical detectors were prepared and subjected to I-V test and energy spectrum measurements at room temperature. The energy spectrum resolutions for the planar detector, unannealed hemispherical detectors, and annealed hemispherical detectors were 27.5%, 15.5%, and 10.9%, respectively, at uncollimated α particles (5.48 MeV) of gamma rays. The results showed that the hemispherical detectors had a higher energy resolution than the planar detector. Rapid annealing played an important role in improving the electrode contact performance and energy resolution. The calculated electron mobility and lifetime product was 6.70 × 10−4 cm2/V.