Improved CdZnTe detectors grown by vertical Bridgman Process

Abstract

AbstractThe γ ray (57Co) and α particle (241Am) detector response of Cdl-xZnxTe crystals grown by vertical Bridgman technique was studied under both positive and negative bias conditions. Postgrowth processing was utilized to produce a high-resistivity material with improved chargecollection properties. Samples of various Zn concentrations were investigated by I-V measurements and thermally stimulated spectroscopies to determine the ionization energies of deep levels in the band gap. When the post-processing conditions were optimized the lowenergy tailing of the γ-ray photopeaks was significantly reduced and an energy resolution of under 5% was achieved for the 122 keV γ-photon line in crystals with x=0.2 Zn content at room temperature. A peak to background ratio of 14:1 for the 122 keV photopeak from 57Co was observed on the best sample, using a standard planar detection geometry. The low-energy 14.4 keV X-ray line could also be observed and distinguished from the noise.