导　　师： 介万奇

学科专业： 080503

授予学位： 博士

作　　者： ;

机构地区： 西北工业大学

摘　　要： Cd/_/(1-x/)Zn/_xTe/(CZT/)晶体具有优异的光电性能，是迄今制造室温X射线及γ射线探测器最为理想的半导体材料。尽管对CZT的研究由来已久，但在CZT晶体的表面处理、金属与CdZnTe晶体接触及In掺杂特性研究上尚存在诸多难题，本文对之进行了探索。 CZT晶体钝化工艺主要是为了减小晶体表面富Te层的电导，减小表面漏电流，提高CZT探测器的性能。钝化可以是物理或者化学过程，可以给晶体表面提供与外界成化学和电学惰性的绝缘层。处理的方法主要有：/(1/)在晶体表面沉积绝缘物质/(ZnS和SiO/_2/)；/(2/)在晶体表面制备本征薄膜层/(氧化物、硫化物以及氟化物/)；/(3/)原位生长宽禁带的Ⅱ-Ⅵ化合物异质结。用NH/_4／H/_2O/_2对CZT晶体钝化，表面主要生成了TeO/_2。钝化后/(/[Cd/]+/[Zn/]/)／/[Te/]原子比接近于1，表明钝化后表面更接近CZT的标准化学计量配比，而且改善了晶体近表面区的晶体结构，同时钝化后明显新增了O的含量。光致发光/(PL/)特性研究结果表明，钝化不仅减小了晶体表面的陷阱态密度，而且减小了与Cd空位复合的深能级杂质浓度。用Agilent 4339B高阻仪进行了CZT晶片I-V特性测试以及Agilent 4294A高精度阻抗分析仪进行了CZT晶片的C-V特性研究，结果表明钝化均能不同程度提高Au／CZT接触的势垒高度，减小漏电流。主要原因是在Au／CZT表面钝化生成的TeO/_2氧化层增加了接触势垒高度，并减小了电荷因隧道效应而穿过氧化层TeO/_2的几率。 采用同步辐射X射线光电子能谱分析结果计算了Au／CZT接触的势垒高度，腐蚀和钝化处理后Au／CZT接触的Schottky势垒高度分别是0.88±0.02 eV和1.17±0.02 eV。根据I-V测试结果计算出钝化前后的Schottky势垒高度分别是0.85±0.02 eV和0.96±0.02eV。用C-V方法测试出钝化前后Schottky势垒高度分别是1.39±0.02 eV和1.51±0.02 eV。 研� Cd/_/(1-x/)Zn/_xTe/(CZT/) possesses excellent optoelectronic properties and is thereforethe most promising material for room temperature X-ray and gamma-ray detectors.Although the study on CZT has lasted for a long period, there still exist someproblems in the surface treatment of CdZnTe crystal, metal-CdZnTe contact propertiesand indium doping behaviors of CZT, which are investigated in this work. The process of passivation had been typically required to reduce the conductivityof Te-riched surface layer of CZT crystal and decrease the surface leakage current.Passivation is a chemical and //or physical process that renders the surface of amaterial chemically and//or electrically inert to its environment. Typical surfacepassivation technologies include the deposition of dielectric materials /(ZnS, SiO/_2/),coating the surface with the native inert films, such as oxides, sulphides and fluorides,and in-situ growth of heterostuctures of wide band gapⅡ-Ⅵcompound. The oxideformed on CZT surface through the passivation treatment with NH/_4//H/_2O/_2 agent isTeO/_2, which offers an inert surface. After passivation,/(/[Cd/]+/[Zn/]/)///[Te/] ratioapproches to 1, which means the stoichiometry composition is restored and thecrystallinity, is improved near the surface. Photoluminescence/(PL/) spectra confirmedthat the passivation treatment minimized the surface trap state density and decreasedthe deep level defects related to recombination of Cd vacancies. I-V and C-Vcharacteristics of Au//CZT contacts with different surface treatments on CZT wafer'ssurface were measured with Agilent 4339B High Resistance Meter and Agilent 4294APrecision Impedance Analyzer, respectively. It was shown that the passivationtreatment increased the barrier height of the Au//CZT contact and decreased theleakage current. The main reason is that higher barrier of Au//CZT contacts decreasesthe possibility for electrons to pass through the sandwich TeO/_2 layer between CZTand Au contact. The interface barrier between Au//CZT contact

关 键 词： 射线和 射线探测器 缺陷 电阻率 光致发光谱 金属 半导体接触 退火 掺杂行为

领　　域： [理学] [理学]