Study on In-Doped CdMgTe Crystals Grown by a Modified Vertical Bridgman Method Using the ACRT Technique.

Pengfei Yu,Biru Jiang,Yongren Chen,Jiahong Zheng,Lijun Luan

doi:10.3390/ma12244236

Abstract

Cadmium–magnesium–telluride (CdMgTe) crystal was regarded as a potential semiconductor material. In this paper, an indium-doped Cd0.95Mg0.05Te ingot with 30 mm diameter and 120 mm length grown by a modified Bridgman method with excess Te condition was developed for room temperature gamma-ray detection. Characterizations revealed that the as-grown Cd0.95Mg0.05Te crystals had a cubic zinc-blende structure and additionally Te-rich second phase existed in the crystals. From the tip to tail of the ingot, the density of Te inclusions was about 103–105 cm−2. The crystals had a suitable band-gap range from 1.52–1.54 eV. Both infrared (IR) transmittance and resistivity were relatively low. Photoluminescence measurement indicated that the ingot had more defects. Fortunately, after annealing, IR transmittance and the resistivity were significantly enhanced due to the elimination of Te inclusions. CdMgTe crystal after annealing showed a good crystal quality. The energy resolutions of the detector for 241Am and 137Cs gamma-ray were 12.7% and 8.6%, respectively. The mobility-lifetime product for electron was 1.66 × 10−3 cm2/V. Thus, this material could be used for room temperature radiation detectors.

Highlights

CdTe-based compound semiconductor materials are usually applied for optical isolators, Faraday rotators, photodetectors, and luminous diodes, especially promising room temperature radiation detectors because of their good optical and electrical properties [1,2,3]
In comparison with CdZnTe, CdMgTe has some advantages, such as ideal energy band gap obtained by using a small amount of Mg in CdTe, appropriate segregation coefficient of Mg [8], and very close lattice constants of CdTe (6.48 Å) and MgTe (6.42 Å) [9]
X-ray diffraction (XRD) patterns of CdMgTe powders which come from different parts of the ingot

Summary

Introduction

CdTe-based compound semiconductor materials are usually applied for optical isolators, Faraday rotators, photodetectors, and luminous diodes, especially promising room temperature radiation detectors because of their good optical and electrical properties [1,2,3]. Cadmium–magnesium–telluride (CdMgTe) as one of the potential radiation detection materials is highly regarded. In the last few decades, CdMgTe crystals were prepared for p-n junction electroluminescent diodes [4,5], mid-infrared solid-state lasers and passive optical Q-switches [6]. Until 2013, Hossain et al [7] firstly reported the development of CdMgTe single crystal for X- and gamma-ray detectors. In comparison with CdZnTe, CdMgTe has some advantages, such as ideal energy band gap obtained by using a small amount of Mg in CdTe, appropriate segregation coefficient of Mg (almost 1.0) [8], and very close lattice constants of CdTe (6.48 Å) and MgTe (6.42 Å) [9]

Methods

Results

Conclusion