光导型碲镉汞探测器的氢化研究

为了提高碲镉汞红外探测器的性能,对ZnS钝化的碲镉汞光导型探测器进行了氢化处理研究,发现处理效果与氢等离子体密度和ZnS钝化层的厚度密切相关。对于ZnS层厚度固定的器件,通过改变氢等离子体密度发现低等离子体密度条件氢化处理更有利于提高器件的性能,表现在处理后器件响应信号提高且噪声下降,从光谱响应上表现为器件短波方向的响应抬高;对于同样的氢化处理条件,通过改变ZnS钝化层的厚度,发现具有较大厚度ZnS层的器件的氢化效果更好。SIMS测试发现氢化过程中氢离子可以穿过ZnS层到达ZnS与碲镉汞的界面处,分析认为氢离子对界面态起到了钝化作用,降低了界面态密度,提高了器件的性能。     

结构和工艺对碲镉汞光导探测器响应率的影响

分析了探测器表面复合和扫出效应对光激发非平衡栽流子寿命和响应率的影响。并进行了实例数字计算,提出了表面和扫出的影响是目前8～14μm碲镉汞光导探测器在工艺和结构上必须予以重视的问题。     

HgCdTe detectors operating above 200 K

This paper reports progress with work aimed at using HgCdTe detector arrays at temperatures above 200 K where cooling is possible with thermo-electric coolers. Both theoretical analysis and calculations based on the detector dark currents indicate that useful performance should be obtainable in this temperature range. However, measurements on the performance of two-dimensional arrays show that the thermal sensitivity degrades rapidly for temperatures above 200 K. The reduction in performance at higher temperatures is shown to be mainly due to increasing 1/f noise as the temperature increases. The noise is characterized as a function of bias and temperature and this is used to predict the noise equivalent temperature difference (NETD) as a function of temperature. We describe an approach for producing two-dimensional arrays based on biasing the detector elements at close to zero bias so that the 1/f noise is minimized. A camera based on this concept is described and an example of the imaging performance is shown.     

碲镉汞高工作温度红外探测器

基于当前红外探测器技术的发展方向,从高工作温度红外探测器应用需求的角度分析了碲镉汞高工作温度红外探测器在组件重量、外形尺寸、功耗、环境适应性及可靠性方面的优势。总结了欧美等发达国家在碲镉汞高工作温度红外探测器研究方面的技术路线及研究现状。从器件暗电流和噪声机制的角度分析了碲镉汞光电器件在不同工作温度下的暗电流和噪声变化情况及其对器件性能的影响;总结了包括基于工艺优化的Hg空位p型n-on-p结构碲镉汞器件、基于In掺杂p-on-n结构和Au掺杂n-on-p结构的非本征掺杂碲镉汞高工作温度器件、基于nBn势垒阻挡结构的碲镉汞高工作温度器件及基于吸收层热激发载流子俄歇抑制的非平衡模式碲镉汞高工作温度器件在内的不同技术路线碲镉汞高工作温度器件的基本原理,对比分析了不同技术路线碲镉汞高工作温度器件的性能及探测器制备的技术难点。在综合分析不同技术路线高温器件性能与技术实现难度的基础上展望了碲镉汞高工作温度器件技术未来的发展方向,认为基于低浓度掺杂吸收层的全耗尽结构器件具备更好的发展潜力。     

HgCdTe红外探测器芯片微管电极的制备与应用

介绍了一种用于超大面阵碲镉汞探测器的新型微管电极。使用常规金属沉积、光刻和刻蚀设备,即可在碲镉汞芯片上制备微管电极。在倒装互连时,碲镉汞芯片通过微管电极插入读出电路上的铟球,实现与读出电路互连。使用微管电极互连,互连所需压力比现有工艺降低了约65 %,并降低了倒装互连工艺对碲镉汞芯片平坦度和互连精度的要求,大幅度提高了互连成功率。     

长波光导HgCdTe红外探测器的可靠性

从真空热浸和电流冲击两个方面对碲镉汞红外探测器进行了研究.真空热浸在星载红外探测器中是十分重要的一项试验,通过研究得到大面积甚长波探测器芯片的耐真空热浸温度为85℃、95℃下39 h的热浸会降低探测器的性能;在电流冲击的实验中,得出低温下探测器芯片耐冲击能力低于室温下的探测器芯片,低温下40 mA的脉冲电流会降低其性能,而室温下相应的脉冲电流为70mA.粘接胶的热导率和厚度是影响耐冲击能力的主要因素.     

碲镉汞探测器的回顾与展望（特邀）

20世纪50年代末,碲镉汞（HgCdTe）合金半导体材料的发明,奠定了热成像的技术和工程应用基础。1975年,美国提出基于第一代红外探测器的热成像通用组件概念——“模块化通用夜视热瞄镜”（Modular Common Thermal Night Sights, MCTNS）,从此HgCdTe材料和探测器被大规模应用于军事领域。从HgCdTe材料的基本物理性质出发,分析了HgCdTe探测器的优点,认为HgCdTe探测器依然是目前性能最好的红外探测器,且正在向多元化方向发展,包括（但不限于）大面阵、平面结和异质结、双波段、甚长波、150 K级工作温度、雪崩探测器等。随着新结构、新模式、新机理、新方法、新工艺的进步,HgCdTe材料和探测器必将达到一个新高度,仍然是第四代主流的红外焦平面探测器。     

HgCdTe/CdZnTe P-I-N high-energy photon detectors

Classical solid-state detection of x-ray and gamma-ray radiation consists of a high voltage applied between two metallic contacts sandwiching a high resistivity, high dielectric strength material; high voltage and high resistivity are required to enable complete charge collection while minimizing the resolution-degrading leakage current (dark current). We report here the conception and successful fabrication and test of a new device construct which changes this paradigm. P-type and n-type layers are fabricated by mercury cadmium telluride (HC.T) liquid phase epitaxy (LPE) on opposite sides of a high-quality wafer of CdZnTe (CZT) in order to construct a p-i-n diode structure. Wafers up to 9 cm² area have been grown. This diode structure provides an extremely high effective resistivity and barrier to the flow of dark current in the device. Several wafer lots have repeatably yielded p-i-n detectors which exhibit typical diode current-voltage (I-V) curves with very low dark currents at very high bias voltages. Spectra obtained from these detectors produce exceptionally sharp photopeaks which exhibit very little low-energy tailing.     

碲镉汞线列红外探测器模块温度循环的可靠性

针对直接倒焊(Ⅰ型)、间接倒焊(Ⅱ型)两种红外探测器模块,两者中的探测器芯片、硅读出电路和引线基板的尺寸完全相同,只在倒焊封装结构上有所差异,用有限元方法分析比较了这两种封装形式的基本模块于液氮温度时的热应力和形变大小情况,分析结果与实验现象符合较好,模块低温形变值的测量验证了有限元分析结果的合理性.     

中波PIN结构碲镉汞雪崩器件变温特性的数值模拟研究

本文对中波HgCdTe APD进行二维数值模拟,通过与实验结果的对比获得80K下PIN结构的APD器件参数。对不同工作温度下的APD器件暗电流机制进行了研究,发现在高工作温度下,影响暗电流的主要是SRH(小偏压)和雪崩机制(大偏压)。对在高工作温度情况下各层参数的变化引起器件性能的变化进行了研究,对不同层厚度、掺杂浓度对器件性能的影响进行了相应理论计算,并对计算结果进行相应的对比研究,获得了理论上最优化的HgCdTe APD高温器件结构,为后续高工作温度的APD器件的研发提供重要参考。     

长波碲镉汞集成偏振探测器的设计

红外探测器已经得到了广泛的应用,近年来,对红外探测器的探测、识别能力提出了更高的要求,迫切需要红外探测器进行创新发展。随着微电子工艺的快速进步,使多种功能的芯片集成在红外探测器上成为可能,也为红外探测器进行创新提供了基础。本文介绍了偏振探测功能在长波碲镉汞探测器上的集成设计、相应的设计验证结果以及成像试验情况,这些工作的介绍为集成红外探测器的开发提供了良好的借鉴。     

碲镉汞线列光导器件的失效模式及原因分析

针对不同项目研制过程中碲镉汞线列光导器件在筛选测试和应用中出现的失效模式进行了归纳和总结,并综合碲镉汞材料参数、器件结构尺寸、器件物理、器件制备工艺和器件测试等几个方面因素对器件失效的可能原因进行了分析,首次提出碲镉汞线列光导器件的优值因子作为失效判据,为进一步理解碲镉汞线列光导器件的物理机理以及更好优化器件的筛选过程提供了参考,为碲镉汞线列光导器件应用中出现的失效问题提供了分析和解决的方向。     

分子束外延HgCdTe nBn结构红外探测器的理论计算和优化

通过2维数值模拟对HgCdTe nBn红外探测器的光电性质进行了研究.理论计算了nBn结构中各层的参数的变化(包含厚度的变化、掺杂浓度的变化以及组分)对器件性能的影响规律.通过优化上述器件结构参数,理论上获得了最优化结构的HgCdTe nBn器件,为获得高性能MBE外延HgCdTe nBn红外探测器提供重要参考.     

碲镉汞光导器件在风云气象卫星中的应用北大核心CSCD

风云气象卫星是中国作为世界大国的“标配”之一,高效服务于我国国民经济和社会发展,有效提升了中国作为世界负责任大国的国际形象。红外探测器作为风云气象卫星的“眼睛”,其性能直接关系到风云卫星的应用效果。碲镉汞光导器件作为第一代光子型红外探测器,在我国风云气象卫星事业的发展壮大中起到了关键作用,尤其是作为全国产化高性能红外探测器,在如今风云变幻的国际环境中更是为我国气象卫星事业的继续发展起到了“定海神针”的作用。本文中以目前在轨运行的风云卫星为基础,概述了在我国风云气象卫星中应用的碲镉汞光导器件的最新性能,也为该系列高性能红外探测器的后续商业化推广应用进行了展望。     

Progress in MOVPE of HgCdTe for advanced infrared detectors

This paper reviews the significant progress made over the past five years in the development of metalorganic vapor phase epitaxy (MOVPE) for the in situ growth of HgCdTe p-n junction devices for infrared detector arrays. The two basic approaches for MOVPE growth of HgCdTe, the interdiffused multilayer process (IMP), and direct alloy growth (DAG) are compared. The paper then focuses on the progress achieved with the IMP approach on lattice-matched CdZnTe substrates. The benefits of the precursors ethyl iodide (EI) and tris-dimethylaminoarsenic (DMAAs) for controlled iodine donor doping and arsenic acceptor doping at dopant concentrations relevant for HgCdTe junction devices are summarized along with the electrical and lifetime properties of n-type and p-type HgCdTe films grown with these precursors. The relative merits of the two CdZnTe substrate orientations we have used, the (211)B and the (100) with 4°–8° misorientation are compared, and the reasons why the (211)B is preferred are discussed. The growth and repeatability results, based on secondary ion mass spectrometry analysis, are reported for a series of double-heterojunction p-n-N-P dual-band HgCdTe films for simultaneous detection in the 3–5 μm and 8–10 μm wavelength bands. Finally, the device characteristics of MOVPE-IMP in situ grown p-on-n heterojunction detectors operating in the 8–12 μm band are reviewed and compared with state-of-the-art liquid phase epitaxial grown devices.     

甚长波碲镉汞光伏探测器伏安特性分析

分析了注入同质结N-on-P和液相外延异质结P-on-N碲镉汞甚长波红外探测器在不同工作温度下的I-V特性,并对R-V特性进行了仿真计算,对比了扩散电流、产生-复合电流、表面漏电流、带间隧穿电流和缺陷辅助隧穿电流等暗电流对两种器件R-V特性的不同影响。     

Numerical analysis of HgCdTe simultaneous two-color photovoltaic infrared detectors

In this paper, we present a physics-based full three-dimensional (3-D) numerical simulation of simultaneous two-color medium-wave infrared long-wave infrared (MWIR-LWIR) and LWIR-very-long-wave infrared (VLWIR) detectors. The present approach avoids geometrical simplifications typical of one- or two-dimensional models that can introduce errors which are difficult to quantify. We include all the relevant material physics and the drift-diffusion equations are solved on a 3-D finite element grid. We simulate device structures that have been fabricated and characterized for operation in the MWIR-LWIR spectral regions and compare the numerical results with the measured values. Furthermore, we apply the same model to predict the performance of similar detector structures intended for operation in the LWIR-VLWIR spectral regions.     

Molecular-beam epitaxial growth and high-temperature performance of HgCdTe midwave infrared detectors

Results are reported on the molecular-beam epitaxial (MBE) growth and electrical performance of HgCdTe midwave-infrared (MWIR) detector structures. These devices are designed for operation in the 140–160 K temperature range with cutoff wavelengths ranging from 3.4–3.8 μm at 140 K. Epitaxial structures, grown at 185°C on (211)B-oriented CdZnTe substrates, consisting of either conventional two-layer P-n configurations or three-layer P-n-N configurations, were designed to examine the impact of device performance on variation of the n-type base layer (absorber) thickness and the inclusion or omission of an underlying wide-bandgap buffer layer. Devices were grown with absorber thicknesses of 3 μm, 5 μm, and 7 μm to examine the tradeoff between the spectral response characteristic and the reverse-bias electrical performance. In addition, 5-μm-thick, wide-bandgap HgCdTe buffer layers, whose CdTe mole fraction was approximately 0.1 larger than the absorber layer, were introduced into several device structures to study the effect of isolating the device absorbing layer from the substrate/growth initiation interface. The MBE-grown epitaxial wafers were processed into passivated, mesa-type, discrete device structures and diode mini arrays, which were tested for temperature-dependent R₀A product, quantum efficiency, spectral response, and the I-V characteristic at temperatures close to 140 K. External quantum efficiencies of 75–79% were obtained with lateral optical-collection lengths of 7 μm. Analysis of the temperature dependence of the diode R₀A product indicates that the device impedance is limited by the diffusion current at temperatures above 140 K with typical R₀A values of 2×10⁶ Ω cm² for a detector cutoff of 3.8 μm at 140 K. An alloy composition anomaly at the absorbing-layer/buffer-layer interface is believed to limit the observed R₀A products to values approximately one order of magnitude below the theoretical limit projected for radiatively limited carrier lifetime. Device electrical performance was observed to be improved through incorporation of a wide-bandgap buffer layer and through reduction of the absorbing layer thickness. An optimum spectral response characteristic was observed for device structures with 5-μm-thick absorbing layers.     

（英）中波碲镉汞光伏探测器的实时gamma 辐照效应

对中波碲镉汞光伏探测器进行了实时gamma 辐照效应研究.通过在辐照过程中对器件的电流—电压特性曲线进行测试,得到了器件电学性能随着gamma辐照剂量的变化.研究发现器件在辐照过程中表现出两种典型的辐照效应: 电离效应和位移效应.电离效应可以通过辐照过程中类似光电流的产生来表现出来,而位移效应则通过辐照过程中器件串联电阻的增加来体现.两种效应都表现为总剂量效应.分析认为,由于位移效应引入的辐照损伤随着辐照剂量的增加越来越多,辐照电离效应产生的自由载流子产额随之逐渐降低,说明随着辐照剂量增加,电离效应逐渐降低,而位移效应则逐渐增强,导致器件性能衰退.     

HgCdTe/Si materials for long wavelength infrared detectors

The heteroepitaxial growth of HgCdTe on large-area Si substrates is an enabling technology leading to the production of low-cost, large-format infrared focal plane arrays (FPAs). This approach will allow HgCdTe FPA technology to be scaled beyond the limitations of bulk CdZnTe substrates. We have already achieved excellent mid-wavelength infrared (MWIR) and short wavelength infrared (SWIR) detector and FPA results using HgCdTe grown on 4-in. Si substrates using molecular beam epitaxy (MBE), and this work was focused on extending these results into the long wavelength infrared (LWIR) spectral regime. A series of nine p-on-n LWIR HgCdTe double-layer heterojunction (DLHJ) detector structures were grown on 4-in. Si substrates. The HgCdTe composition uniformity was very good over the entire 4-in. wafer with a typical maximum nonuniformity of 2.2% at the very edge of the wafer; run-to-run composition reproducibility, realized with real-time feedback control using spectroscopic ellipsometry, was also very good. Both secondary ion mass spectrometry (SIMS) and Hall-effect measurements showed well-behaved doping and majority carrier properties, respectively. Preliminary detector results were promising for this initial work and good broad-band spectral response was demonstrated; 61% quantum efficiency was measured, which is very good compared to a maximum allowed value of 70% for a non-antireflection-coated Si surface. The R₀A products for HgCdTe/Si detectors in the 9.6-μm and 12-μm cutoff range were at least one order of magnitude below typical results for detectors fabricated on bulk CdZnTe substrates. This lower performance was attributed to an elevated dislocation density, which is in the mid-10⁶ cm⁻² range. The dislocation density in HgCdTe/Si needs to be reduced to <10⁶ cm⁻² to make high-performance LWIR detectors, and multiple approaches are being tried across the infrared community to achieve this result because the technological payoff is significant.