Improved electrical properties of detector-grade Cd1−xZnxTe single crystals passivated by KMnO4 and K2S2O8 solutions

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 2023-06, Vol.1051, Article 168229
• Main Authors: Yu, Pengfei, Yang, Guizhi, Sun, Xing, Rao, Tianjing, Fu, Haijia, Luan, Lijun, Li, Hui
• Format: Article
• Language: English
• Subjects: Cd1−xZnxTe single crystals; Energy resolution; Leakage current; Passivation; Surface treatment
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2023.168229

Surface treatment is very important for detector-grade Cd1−xZnxTe crystals. In this paper, electrical properties of detector-grade Cd1−xZnxTe single crystals passivated by KMnO 4 and K2S2O8 solutions were investigated. Four passivation agents, H2O2, (NH4)2S, KMnO 4 and K2S2O8, were compared. The results indicated that the leakage current decreased obviously after passivation. It was found that KMnO 4 and K2S2O8 had better passivation effect. When the passivation time was 1 min and 2 min, KMnO 4 had the best passivation effect, and the leakage current of Cd1−xZnxTe crystal was as low as 1.3 nA. However, when the passivation time was 5 min, the passivation effect of K2S2O8 was the best, and the leakage current was as low as 0.7 nA. The chemical reactions of KMnO4 and K2S2O8 with Cd1−xZnxTe crystals were proposed due to XPS analysis. PL spectra showed that the surface properties of the Cd1−xZnxTe crystals changed obviously after passivation. 241Am γ-ray @59.5 keV energy resolution of the detectors fabricated with the crystals passivated by KMnO 4 and K2S2O8 solutions for 5 min were notably improved. In particular, the energy resolution of Cd1−xZnxTe planar detector with K2S2O8 passivation could reach 8.03% and was improved by 236%. •Surface treatment is very important for room temperature detectors.•Electrical properties of passivated detector-grade Cd1−xZnxTe single crystals were investigated.•Four passivation agents, H2O2, (NH4)2S, KMnO4 and K2S2O8, were compared.•The leakage current decreased obviously after passivation.•Energy resolution of the detectors passivated by KMnO4 and K2S2O8 solutions were notably improved.