Ti/Au复合电极在CdZnTe (111)B面上的表面结构与性能研究

摘要/Abstract

摘要： 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。

关键词: CdZnTe, Ti/Au, 接触界面, 欧姆特性, 晶格失配层, 互扩散

Abstract: 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.

Key words: CdZnTe, Ti/Au, contact interface, ohmic characteristic, lattice mismatch layer, interdiffusion

中图分类号:

TL81
O646.5

陶思祺, 张继军, 王淑蕾, 秦美琪, 邱攀辉, 宋晓龙. Ti/Au复合电极在CdZnTe (111)B面上的表面结构与性能研究[J]. 人工晶体学报, 2021, 50(6): 1089-1095.

TAO Siqi, ZHANG Jijun, WANG Shulei, QIN Meiqi, QIU Panhui, SONG Xiaolong. Surface Structure and Properties of Ti/Au Composite Electrode on CdZnTe (111)B Surface[J]. JOURNAL OF SYNTHETIC CRYSTALS, 2021, 50(6): 1089-1095.

参考文献

[1] SCHLESINGER T E, TONEY J E, YOON H, et al.Cadmium zinc telluride and its use as a nuclear radiation detector material[J].Materials Science and Engineering:R:Reports, 2001, 32(4/5):103-189.
[2] AISSAT A, FATHI M, VILCOT J P.Design and simulation of Cd_1-xZn_xTe thin films epitaxied on CdTe substrate for photovoltaic devices applications[J].Energy Procedia, 2013, 36:86-93.
[3] 杨帆,王涛,周伯儒,等.室温核辐射探测器用碲锌镉晶体生长研究进展[J].人工晶体学报,2020,49(4):561-569.
YANG F, WANG T, ZHOU B R, et al.Research progress on CdZnTe crystal growth for room temperature radiation detection applications[J].Journal of Synthetic Crystals, 2020, 49(4):561-569(in Chinese).
[4] ZHA G Q, JIE W Q, TAN T T, et al.The interface reaction and Schottky barrier between metals and CdZnTe[J].The Journal of Physical Chemistry C, 2007, 111(34):12834-12838.
[5] QIN K F, WANG L J, ZHANG J J, et al.A two-step deposition process for electrode fabrication of CdZnTe detectors[J].Vacuum, 2012, 86(7):827-829.
[6] ABBENE L, DEL SORDO S, FAUCI F, et al.Spectroscopic response of a CdZnTe multiple electrode detector[J].Nuclear Instruments and Methods in Physics Research Section A:Accelerators, Spectrometers, Detectors and Associated Equipment, 2007, 583(2/3):324-331.
[7] LING L W, ZHANG J J, ZHAO S H, et al.Surface analysis and electrical measurement of the ohmic contact on p-CdZnTe (111)B face with Au/Cd composite electrode[J].Materials Science in Semiconductor Processing, 2019, 98:90-94.
[8] YANG L Q, MIN J H, LIANG X Y, et al.Investigation on the contact interface of Au/Zn on CdZnTe (111)B surface[J].Materials Science in Semiconductor Processing, 2017, 67:175-180.
[9] JUNG I, KRAWCZYNSKI H, BURGER A, et al.Detailed studies of pixelated CZT detectors grown with the modified horizontal Bridgman method[J].Astroparticle Physics, 2007, 28(4/5):397-408.
[10] BEILICKE M, DE GERONIMO G, DOWKONTT P, et al.Performance of pixelated CZT detectors as a function of pixel and steering grid layout[J].Nuclear Instruments and Methods in Physics Research Section A:Accelerators, Spectrometers, Detectors and Associated Equipment, 2013, 708:88-100.
[11] SHI H Z, WANG S L, ZHANG J J, et al.Investigation on the rapid annealing of Ti-Au composite electrode on n-type (111) CdZnTe crystals[J].Crystals, 2020, 10(3):156.
[12] ZHENG Q, DIERRE F, CROCCO J, et al.Influence of surface preparation on CdZnTe nuclear radiation detectors[J].Applied Surface Science, 2011, 257(20):8742-8746.
[13] XU H T, XU R, HUANG J, et al.The dependence of Zn content on thermal treatments for Cd_1-xZn_xTe thin films deposited by close-spaced sublimation[J].Applied Surface Science, 2014, 305:477-480.
[14] MOGER S N, SHANUBHOGUE D U, KESHAV R, et al.Spectroscopic and electrical analysis of vacuum co-evaporated Cd_xZn_1-xTe thin films[J].Superlattices and Microstructures, 2020, 142:106521.
[15] YASAR B, ERGUNT Y, KABUKCUOGLU M P, et al.HRTEM analysis of crystallographic defects in CdZnTe single crystal[J].Journal of Electronic Materials, 2018, 47(1):778-784.
[16] BELL S J, BAKER M A, DUARTE D D, et al.Comparison of the surfaces and interfaces formed for sputter and electroless deposited gold contacts on CdZnTe[J].Applied Surface Science, 2018, 427:1257-1270.
[17] AL-SHIBANI K M.Effect of isothermal annealing on CdTe and the study of electrical properties of Au-CdTe Schottky barriers[J].Physica B:Condensed Matter, 2002, 322(3/4):390-396.
[18] XI S Z, JIE W Q, ZHA G Q, et al.Mechanism of low Schottky barrier formation for chromium/CdZnTe contact[J].The Journal of Physical Chemistry C, 2014, 118(10):5294-5298.
[19] 陈继权,孙金池,李阳平,等.CdZnTe晶体欧姆接触电极的制备工艺研究[C]//第五届中国功能材料及其应用学术会议,2004:349-352.
CHEN J Q, SUN J C, LI Y P, et al.Preparation technology of CdZnTe crystal ohmic contact electrode[C]//5th China Conference on Functional Materials and Their Applications, 2004:349-352(in Chinese).
[20] 段宝兴,杨银堂.CMOS双层可变功函数金属栅技术[J].功能材料与器件学报,2010,16(2):158-162.
DUAN B X, YANG Y T.CMOS Bi-layer metal gate technology with tunable work function[J].Journal of Functional Materials and Devices, 2010, 16(2):158-162(in Chinese).
[21] XI S Z, JIE W Q, WANG T, et al.Studies on Cr electrode of CdZnTe detector for high energy radiation detection[J].Journal of Materials Science:Materials in Electronics, 2018, 29(6):5049-5056.