Point Defects in Pb-, Bi-, and In-Doped CdZnTe Detectors: Deep-Level Transient Spectroscopy (DLTS) Measurements

Abstract

We studied, by current deep-level transient spectroscopy (I-DLTS), point defects induced in CdZnTe detectors by three dopants: Pb, Bi, and In. Pb-doped CdZnTe detectors have a new acceptor trap at around 0.48 eV. The absence of a V Cd trap suggests that all Cd vacancies are compensated by Pb interstitials after they form a deep-acceptor complex [[Pb Cd ] + -V Cd 2À ] À . Bi-doped CdZnTe detectors had two distinct traps: a shallow trap at around 36 meV and a deep donor trap at around 0.82 eV. In detectors doped with In, we noted three well-known traps: two acceptor levels at around 0.18 eV (A-centers) and 0.31 eV (V Cd ), and a deep trap at around 1.1 eV.

Defect Levels in Nuclear Detector Grade Cd0.9Zn0.1Te Crystals

“…Defect levels D 1 and D 2 are related to the so-called A centers in the CZT crystals affected by Cd vacancies and shifted by In doping. 8,[12][13][14][15][16] Defect level D 3 has been attributed to a V Cd − or V Cd 2− defect in the literature, 17,18 and may be related to the A center levels. Defect levels D 4 -D 8 have been observed to be related to the V Cd 2− defect, 8,13,[15][16][17][18][19][20] however defect level D 4 has also been theoretically calculated to be related to a Te-Te split bonding complex energy level.…”

Effect of CZT Powder Burying CZT Crystal on Annealing in Cd Atmosphere

“…Due to the inevitable introduction of volume defects (Te inclusions) [5] and deep-level defects (V Cd , Te Cd , etc.). [6][7][8] These volume defects or point defects may become trap centers, DOI: 10.1002/crat.202300054 causing distortion of the electric field in the crystal, deteriorating the carrier transport ability near itself, and seriously deteriorating the performance of the detector when the concentration reaches a higher concentration. [9,10] Its formation is mainly due to the fact that when the crystal is in the cooling stage, the Terich phase shrinks, the solid solubility of Te decreases, and the supersaturated Te precipitates out to form Te inclusions, which cannot be avoided during the crystal growth process.…”

Large Size Crystal Growth, Photoluminescence, Crystal Excellence, and Hardness Properties of In-Doped Cadmium Zinc Telluride

“…In earlier eras, various kinds of research and development have been done on CdZnTe (CZT) and its related compounds to achieve a good quality RT X-ray and γ-ray detector-grade single crystals that also can be applied in key applications. − The single crystals of CZT have been grown by different techniques, such as high-pressure vertical Bridgman, modified vertical Bridgman (MVB) technique, traveling heater method, , electrodynamic gradient freeze (EDG) furnace, vapor growth, and oscillatory Bridgman technique. , The analysis on grown CZT crystal shows that the crystals possess grain boundaries and other imperfections like: great Te inclusions, twin, and dislocations that makes limited use of CZT. ,− Among all these technique vertical gradient freezing (VGF) − is found to have better results in terms of good quality with less defects crystals for detection applications. The single crystals of CZT with different dopants such as, Bi, In, Ti, Pb, etc., were grown by oscillatory Bridgman technique, high-pressure, modified and vertical Bridgman methods. − It is well-known in the literature that CZT:In is a key artistic material for nuclear radiation detection at RT. However, there is no/least report available for In-doped CZT in which the correlation between growth, optical, excellent quality and strength, etc.…”