Ti/Au复合电极在CdZnTe(111)B面上的表面结构与性能研究

近年来,碲锌镉(CdZnTe)材料制成的探测器已经成为研究热点,适当的接触特性已经成为提高探测器性能的关键问题。本文主要探讨了弱n型CdZnTe晶体(111)B面Ti/Au复合电极的欧姆接触性能,采用两步沉积工艺制备Ti/Au复合电极。通过AFM、FIB/TEM、XPS、I-V等测试方法研究了电极与CdZnTe的界面结构、化学成分和电学性能。结果表明,Ti过渡层的引入可以减轻和改善晶片抛光过程中形成的损伤层,增加了电极与晶体之间的欧姆特性。相比于CdZnTe (111)B面上的Cr/Au复合电极,Ti/Au复合电极的粗糙度更低、接触界面更平整,晶格失配层厚度也更低。Ti中间层促进了金/半界面的互扩散现象, 有利于增加黏附性和降低肖特基势垒,并且在Ti/Au复合电极与CdZnTe接触的界面上没有观察到氧元素的存在。I-V测试表明Ti/Au复合电极具有更加良好的欧姆特性和更低的肖特基势垒。

Surface Structure and Properties of Ti/Au Composite Electrode on CdZnTe (111)B Surface

In recent years, detectors made from cadmium zinc telluride (CdZnTe) have become a research focal point, and proper contact characteristics have become a key issue for improving the performance of the detector. This paper mainly discusses the ohmic contact performance of Ti/Au composite electrode on the weak n-type CdZnTe crystal (111)B surface, preparation of Ti/Au composite electrode by two-step deposition process.Through AFM, FIB/TEM, XPS, I-V and other test methods, the interface structure, chemical composition and electrical properties of the interface between the electrode and CdZnTe were studied. The results show that the introduction of the Ti transition layer can reduce and improve the damage layer formed during the wafer polishing process, and increase the ohmic characteristics between the electrode and the crystal. Compared with the Cr/Au composite electrode on the CdZnTe (111)B surface, the Ti/Au composite electrode has a lower roughness, a smoother contact interface, and a lower thickness of the lattice mismatch layer. The Ti intermediate layer promotes the interdiffusion phenomenon of the gold/half interface, which is beneficial to increase the adhesion and reduce the Schottky barrier, and the presence of oxygen is not observed at the interface between the Ti/Au composite electrode and the CdZnTe contact.The I-V test shows that the Ti/Au composite electrode has better ohmic characteristics and lower Schottky barrier.