硅酸盐学报

室温辐射探测器用CdMgTe单晶质量提升策略

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李玉婷 ¹ , 俞鹏飞 ¹ , 韩召 ¹ , 徐清阳 ¹ , 鲍赟震 ¹ , 介万奇 ²

硅酸盐学报 | 研究论文 2025,53(7): 1981-1992

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硅酸盐学报 |研究论文 2025 , 53 (7) : 1981 -1992

室温辐射探测器用CdMgTe单晶质量提升策略

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李玉婷¹, 俞鹏飞¹, 韩召¹, 徐清阳¹, 鲍赟震¹, 介万奇²

作者信息

^1．长安大学材料科学与工程学院，西安 710064

^2．西北工业大学凝固技术全国重点实验室，西安 710072

通讯作者:

俞鹏飞（1982—），男，博士，副教授。

作者简介:

李玉婷（2001—），女，硕士研究生。

Strategy for Enhancing the Quality of CdMgTe Single Crystals for Room-Temperature Radiation Detectors

Yuting LI¹, Pengfei YU¹, Zhao HAN¹, Qingyang XU¹, Yunzhen BAO¹, Wanqi JIE²

Affiliations

^1.School of Materials Science and Engineering, Chang'an University, Xi'an 710064, China

^2.State Key Laboratory of Solidification Technology, Northwestern Polytechnical University, Xi'an 710072, China

Corresponding Author:

YU Pengfei (1982-), male, Ph.D., Associate Professor. E-mail: yupengfei@chd.edu.cn

LI Yuting (2001-), female, Master candidate. E-mail: liyuting123@chd.edu.cn

出版时间: 2025-07-20 doi: 10.14062/j.issn.0454-5648.20240756

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摘要

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碲镁镉（CdMgTe）晶体是一种理想的室温辐射探测新材料。为了提升晶体质量和探测器性能，采用Se气氛对CdMgTe晶体进行退火改性。退火后，Se以化学吸附的形式部分取代了Te，晶体中Mg和Se元素含量增加，禁带宽度最多增加了0.042 eV。随着退火时间的延长，Te夹杂相密度不变，红外透过率和显微硬度先减小后增大，电阻率逐渐降低。最佳退火条件为Se气氛下773 K退火120 h，此时晶体质量最好，红外透过率达63.6%。由该晶体制备的室温辐射平面探测器性能最佳，电子迁移率达344.47 cm²/（V·s），对能量为5.48 MeV的²⁴¹Am α粒子的能量分辨率和载流子迁移率寿命积（μτ）_e分别为17.2%和1.32×10^-4 cm²/V。

关键词

室温辐射探测器 / 碲镁镉晶体 / 硒气氛退火 / 电阻率

Abstract

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Introduction

Cadmium magnesium telluride (CdMgTe), as a group II-VI CdTe-based compound semiconductor, can be used in room-temperature radiation detection. However, CdMgTe crystals grown by melt methods often exhibit major defects like vacancies, dislocations, twins, and inclusions, severely impacting the crystal quality and detector performance. Some studies show that selenium (Se) can significantly reduce harmful defects like sub-boundary networks and Te inclusions in CdTe-based crystals, enhancing the crystal quality through its favorable segregation coefficient and intense solid-solution hardening effect. Therefore, in this paper, Se was introduced into CdMgTe crystals via vapor phase diffusion as an advanced annealing strategy to enhance the both crystal quality and detector performance. In addition, the effect of annealing time on the crystal defects, microhardness, optical and electrical properties, and detector performance was also investigated.

Methods

The annealing source was a high-purity Se (7N), and the slices with the dimensions of 5 mm×5 mm×2 mm were selected from an In-doped CdMgTe ingot grown by a modified vertical Bridgman method under Cd excess condition. Prior to annealing, the slices were mechanically polished with an MgO suspension and then treated with a 2% Br₂-MeOH solution to eliminate scratches and any damaged layers. The slices and the source were positioned at opposite ends of a quartz annealing device, with quartz crucibles evacuated to a pressure of 10^-5 Pa. The annealing temperature of both slice and source was selected at 773 K. Effect of annealing time on CdMgTe crystal properties was investigated at different holding time (i.e., 30, 60, 120 h, and 240 h). CdMgTe planar room-temperature radiation detectors were fabricated via evaporating Au electrodes onto the both sides of the annealed crystals.

CdMgTe crystals before and after annealing in Se atmosphere were characterized by near-infrared spectrometry (NIR), X-ray photoelectron spectroscopy (XPS), infrared transmission microscopy (IRTM), field emission scanning electron microscopy (FESEM), infrared (IR) spectrometry, Raman spectrometry, and current-voltage (I-V) measurement. Room-temperature radiation detectors were prepared by evaporation of Au electrodes on both sides of CdMgTe crystals. The carrier mobility was determined by a time-of-flight (TOF) technology. The energy spectrum of the detectors was acquired by an ORTEC measurement system with uncollimated ²⁴¹Am α particles with an energy of 5.48 MeV as an irradiation source.

Results and discussion

The band gap of the as-grown crystal is 1.505 eV, and annealing in Se atmosphere does not prevent the volatilization of Cd in CdMgTe crystals or reduce Te inclusions. After annealing, the maximum increase of the band gap is 0.042 eV. Se interacts with CdMgTe matrix via diffusion and chemisorption, forming chemical bonds that effectively result in the partial substitution of Se for Te., The solution strengthening effect of Se is more pronounced than that of Mg as the annealing time increases, causing that the microhardness initially decreases and then increases, which is lower than that of the as-grown crystal. The IR transmittance of the crystal after 120 h annealing is 63.6%, which approaches the theoretical value of 65%, thus satisfying a criterion for high-quality crystals. The peak intensity of A₁(Te) is basically unchanged based on the Raman spectra. However, an increase in the peak intensity of TO(CdTe) and a decrease in that of LO(CdTe) indicate that the lattice integrity in the annealed crystal is compromised.

CdMgTe crystal obtained under optimal annealing conditions is fabricated into an Au/CdMgTe/Au planar structure for the room-temperature radiation detector. TOF measurements show a remarkable increase in electron mobility (μ_e), up to 344.47 cm²/(V·s). ²⁴¹Am α particle source with an energy of 5.48 MeV is used for detector energy spectrum testing. The optimal CdMgTe detector exhibits the performance with an energy resolution of 17.2% and a carrier mobility lifetime product (μτ)_e of 1.32×10^-4 cm²/V. Annealing in a Se atmosphere can thus offer an effective approach to enhance the quality of CdTe-based crystals.

Conclusions

An advanced annealing strategy was adopted for enhancing the quality of CdMgTe single crystals for room-temperature radiation detectors. After annealing, a decrease in Cd content along with an increase in Mg content resulted in an expanded band gap. The microhardness and the IR transmittance of the crystals firstly decreased and then increased, and the resistivity gradually decreased as the annealing time increased, thus improving the crystal quality. The optimum condition of Se atmosphere annealing was at 773 K for 120 h. The optimal performance of the detector was an electron mobility (μ_e) of 344.47 cm²/(V·s), an energy resolution of 17.2%, and a (μτ)_e product of 1.32×10^-4 cm²/V for ²⁴¹Am α particles with an energy of 5.48 MeV.

Key words

room-temperature radiation detector / cadmium magnesium telluride crystals / selenium atmosphere annealing / resistivity

引用本文

李玉婷, 俞鹏飞, 韩召, 徐清阳, 鲍赟震, 介万奇. 室温辐射探测器用CdMgTe单晶质量提升策略. 硅酸盐学报, 2025 , 53 (7) : 1981 -1992 . DOI: 10.14062/j.issn.0454-5648.20240756

Yuting LI, Pengfei YU, Zhao HAN, Qingyang XU, Yunzhen BAO, Wanqi JIE. Strategy for Enhancing the Quality of CdMgTe Single Crystals for Room-Temperature Radiation Detectors[J]. Journal of the Chinese Ceramic Society, 2025 , 53 (7) : 1981 -1992 . DOI: 10.14062/j.issn.0454-5648.20240756

基金

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西北工业大学凝固技术全国重点实验室开放课题(SKLSP202318)
长安大学大学生创新训练计划项目(202410710098)

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2025年第53卷第7期

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文章信息

doi: 10.14062/j.issn.0454-5648.20240756

接收时间：2024-11-28
首发时间：2026-10-21
出版时间：2025-07-20

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收稿日期：2024-11-28
修回日期：2024-12-27

基金

西北工业大学凝固技术全国重点实验室开放课题(SKLSP202318)

长安大学大学生创新训练计划项目(202410710098)

作者信息

^1．长安大学材料科学与工程学院，西安 710064

^2．西北工业大学凝固技术全国重点实验室，西安 710072

通讯作者:

俞鹏飞（1982—），男，博士，副教授。

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https://castjournals.cast.org.cn/joweb/gsyxb/CN/10.14062/j.issn.0454-5648.20240756

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2种不同金属材料的力学参数

科 Family	属数 Number of genus	种数 Number of species	占总种数比例 Percentage of total species (%)	属 Genus	种数 Number of species	占总种数比例 Percentage of total species (%)
鹅膏菌科Amanitaceae	2	11	5.26	鹅膏菌属 Amanita	10	4.78
小菇科 Mycenaceae	2	12	5.74	丝盖伞属 Inocybe	5	2.39
多孔菌科 Polyporaceae	8	14	6.70	蜡蘑属 Laccaria	5	2.39
红菇科 Russulaceae	3	23	11.00	小皮伞属 Marasmius	6	2.87
				小菇属 Mycena	11	5.26
				光柄菇属 Pluteus	5	2.39
				红菇属 Russula	17	8.13
				栓菌属 Trametes	5	2.39

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