Development of highly reliable contacts on p-type CdTe for radiation detectors

开发用于辐射探测器的 p 型 CdTe 高度可靠触点

• 批准号: 13450287
• 负责人: MURAKAMI Masanori
• 金额: $ 9.15万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13450287/
• 关键词: radiation detectors; CdTe; contact materials

Cadmium telluride (CdTe) is an attractive semiconductor material for X-ray and γ-ray radiation detectors. The advantages of CdTe are that it has a large bandgap energy (〜1.6eV) and a high average atomic number (Z_<cdTe>=50). However, due to the low mobility and short lifetime of holes in CdTe, a considerable amount of charge loss causes reduction of energy resolution in the detector. For a complete charge collection, very high bias voltage must be applied in the CdTe detectors. Thus, Schottky contacts, which provide very low leakage current with a high bias voltage, are required to achieve high resolution in CdTe detectors. Although the conventional approach to fabricate Schottky contacts for p-type CdTe involves the use of metals with low work function, such as indium (In), the time-dependent degradation of detection performance during device operation, known as "polarization effect", is often observed in the CdTe detectors with Schottky contacts. In order to apply CdTe to practical r … More adiation detector, highly stable Schottky contacts with low leakage current must be developed.The purpose of the present study is twofold. The first is to develop of highly reliable Schottky In contacts for CdTe radiation detectors. The second is to understand the Schottky In contact formation mechanism by analyzing interfacial micro structure of the In films which were deposited at various substrate temperatures using X-ray diffraction (XRD) and transmission electron microscopy (TEM). These studies will provide us a guideline for developing Schottky contacts for p-type CdTe which would be used hi the radiation detectors.The thermal treatment of the CdTe during the depositions of In remarkably decreased the leakage current and improved its stability. XRD analysis showed that In atoms reacted with CdTe forming In_4Te_3 or InTe during the depositions with T_S>200℃. The InTe contacts, which were prepared by the depositions with rather high T_s, drastically improved the stability of the detection performance. TEM observations revealed that the leakage current and the stability of the CdTe radiation detectors were strongly correlated with the micro structure of contact/CdTe interfaces. Less

池尿酸镉（CDTE）是X射线和射线辐射探测器的有吸引力的半导体。在CDTE中，Casses Casses Casses检测器的浓度损失量，必须在CDTE探测器中使用非常高的偏置电压，因此，Schottky接触率很低用于制造schottky接触的方法P型CDTE CDTE CDTE涉及使用低工作fuk函数的金属，例如indium（in），依赖于检测设备设备设备操作的时间，称为“极化效应”，是观察者VED在带有schottky的CDTE探测器中。 [通过分析使用X射线衍射（XRD）任务电子显微镜（TEM）的膜底物底物温度（TEM），这些研究将在膜中分析接触形成机械的schottky。对于p型CDTE CDTE将用于辐射探测器。在显着降低泄漏电流的沉积过程中，CDTE的热处理XRD分析表明，在CDTE形成IN_4TE_3或INTE期间， T_S> 200°C的沉积。通过相当高的T_S制备的Inte接触，Drasticaly提高了检测性能的稳定性，发现CDTE辐射范围与Micro结构较少相关。