Vanadium-Doped Cadmium Manganese Telluride (Cd1−x Mn x Te) Crystals as X- and Gamma-Ray Detectors

Abstract

CdMnTe offers several potential advantages over CdZnTe as a roomtemperature gamma-ray detector, but many drawbacks in its growth process impede the production of large, defect-free single crystals with high electrical resistivity and high electron lifetimes. Here, we report our findings of the defects in several vanadium-doped as-grown as well as annealed Cd 1Àx Mn x Te crystals, using etch pit techniques. We carefully selected single crystals from the raw wafer to fabricate and test as a gamma-ray detector. We describe the quality of the processed Cd 1Àx Mn x Te surfaces, and compare them with similarly treated CdZnTe crystals. We discuss the characterization experiments aimed at clarifying the electrical properties of fabricated detectors, and evaluate their performance as gamma-ray spectrometers.

Vertical Bridgman growth and characterization of CdMnTe crystals for gamma-ray radiation detector

“…It has greater tunability of the band gap in the range 1.7-2.2 eV due to the large compositional influence of manganese, thus the energy band gap of CMT increases about 13 meV per atomic percent of Mn compared with 6.7 meV of Zn in CZT [1]. Another significant advantage of CMT is the near unity segregation coefficient of Mn in CdTe in contrast with 1.3 of Zn in CdTe [2]. With the characters of CMT, it is easy to grow uniform large-volume single crystal, which can potentially fabricate into high-performance gamma-ray spectrometers.…”

“…Development of detector-grade CMT crystals suffers from its low resistivity and poor charge carrier transport properties, so previous studies of CMT bulk crystals have concentrated on obtaining high resistivity and good mobility-lifetime products [2,3]. In order to get high-resistivity CMT crystals, indium was adding to the starting materials to compensate for the cadmium vacancies, because Cd has the highest partial vapor pressure among the CMT melt constituents and the escape of Cd atoms from ingots will cause native Cd vacancies, which affects the resistivity and conductivity type of CdMnTe crystal.…”

Structural, electrical, and optical properties of CdMnTe crystals grown by modified floating-zone technique

“…[1][2][3] Recently, CMT has attracted increasing interest since it is considered a promising material for the fabrication of high-performance room-temperature x-ray and gammaray detectors. [2][3][4][5] Such detectors offer great potential for nonproliferation applications, medical imaging, astrophysics research, and monitoring industrial processes, because they are able to operate at ambient temperatures, while providing a high detection efficiency and good energy resolution. [6,7] Compared with cadmium zinc telluride (CdZnTe or CZT), a current leading material in such applications, CMT offers several distinct advantages that make it a good candidate in this field.…”

Comparison of cadmium manganese telluride crystals grown by traveling heater method and vertical Bridgman method

“…Currently, the CdMnTe crystal is usually grown by the Vertical Bridgman (VB) method [8,9]. The method has the advantages of its simplicity and capability of adjusting the growth temperature gradient and velocity.…”