激光束感应电流法研究HgCdTe电活性缺陷和焦平面器件的光电特性

用高分辨率的、非破坏的光学表征技术的激光束感应电流研究碲镉汞(MCT)晶片中电活性缺陷和光伏型红外碲镉汞焦平面器件及光伏型硅光电器件P-N结光电特性,实验表明在MCT晶片中探测到激光束感应电流,在光伏型P-N结构的器件中,观察到周期结构的激光束感应电流分布.定性地观察激光束感应电流图谱以及定量地分析单个P-N结的感应电流分布形状可以判断器件的均匀性和器件的质量.     

第三代碲镉汞器件的研发进展

通过对近年来部分英语文献的归纳分析,介绍了国外第三代碲镉汞（MCT）器件的研发现状,包括具有新颖器件结构的双色或三色探测器、雪崩光电二极管和多光谱阵列等.分析了三代MCT器件在阵列规模、光伏技术的甚长波应用、多色、读出电路等方面的研究进展.指出利用复杂可控的气相外延生长方法,例如分子束外延（MBE）和金属有机气相化学沉积（MOCVD）等,已可制备近乎理想设计的异质结光电二极管.随着基于MBE生长的MCT技术发展,法国和美国已分别可以制备4英寸以上的大尺寸锗基和硅基晶片,并在晶片上以可控厚度沉积光敏薄膜.依据目前的发展,三代MCT技术有望3、5年内达到量产的水平.     

劳厄形貌术在碲镉汞器件研制中的应用

讨论了反射劳厄形貌术的优缺点，结合碲镉汞器件研制工作给出了实际应用的几个例子。如磅镉汞晶片结构检查，观察碲镉汞晶片表面的磨抛损伤、跟踪观察碲镉汞晶片在光刻、化学腐蚀成形、离子刻蚀成形前后的晶格变化等。     

制备HgCdTe红外焦平面器件的离子注入技术

1 前言 啼镉汞光伏型红外焦平面列阵器件(IRF-PAs)是以外延材料为基础发展起来的,其基本工作原理利用了P-n结的光电效应。目前,碲镉汞光伏型红外焦平面的器件结构主要是离子注入形成的n-on-p和p-on-n平面结。虽然现在已     

劳厄形貌术在碲镉汞器件研制中的应用（二）

讨论了反射劳厄形貌术的优缺点，结合碲镉汞器件研制工作给了实际应用的几个例子。如磅镉汞晶片结构检查，观察磅镉汞晶片的磨势损伤，跟踪观察磅镉汞晶片在不光刻、化学腐蚀成形、离子刻蚀成表前后的晶格变化等。     

N型碲镉汞材料的少子寿命分布测量

目前,碲镉汞已被广泛用于制造热成象中采用的光子探测器。而在光子探测器的性能中,少子寿命是一个重要参数。在光电导器件中,探测率正比于τ(1/2)。而当光导器件工作在“扫出”方式时,要达到“扫出”而所件中,需的电场正比于τ(-1)。在扫积型(SPRITE)器等效背景限探测器数目正比于τ(1/2)。在光伏器件中,τ也是一个重要参数,因为它决定了扩散长度及少子收集效率。因此人们希望能够确定碲镉汞的寿命,从而有助于选取好的材料。所以我们开发了一种测量从原始晶锭上切下来的N型碲镉汞晶片的寿命分布技术。     

对两类MCT红外探测器的剖析

用剖析法观察了两类光伏型红外碲镉汞(MCT)探测器晶片:一类其D~*在1×10~8～5.9×10~9cm Hz~(1/2)/W之间,λ。在8～13.8μm范围内;另一类是无P—N结特性的。观察结果表明:前一类晶片(以后简称为“有信号”的)相对辐照方向具有[111]取向;而后一类晶片(简称为“无信号”的)其取向是无规则的。本文从晶体中原子排布及缺陷(位错)的特点,初步讨论了晶片取向对探测器性能的影响。     

碲镉汞晶片少数载流子寿命面分布的自动测试技术

建立了一套碲镉汞薄晶片加工过程中的少数载流子寿命面分布自动检测系统，用于碲镉汞我元光导器件制备工艺生产线，获得了１８０地器件性能分布同薄晶片少数载流子寿命分布一致的结果。     

MS界面输运特性对碲镉汞光伏器件I—V特性的影响

根据金属－碲镉汞接触的基本电流－电压关系,深入讨论了金属－半导体（MS）接触界面输运特性对碲镉汞光伏器件I－V特性的影响,并对实际器件的测量数据进行了分析比较。     

用DLTS法研究碲镉汞的深能级

用深能级瞬态谱(DLTS)方法研究了高镉组份碲镉汞混晶(Hg_(1-x)Cd_xTe,0.55≤x≤0.84)的深能级。实验所用碲镉汞晶体用固态再结晶法制备,晶片未经定向,实验用器件在单晶粒上制作以避免晶粒间界的影响。材料未经有意掺杂,生长出来的晶体为P型,为获得N型晶片,可     

A discrete element model of laser beam induced current (LBIC) due to the lateral photovoltaic effect in open-circuit HgCdTe photodiodes

The non-destructive optical characterization technique of Laser-Beam-Induced-Current (LBIC) imaging has proven useful in qualitatively assessing electrically active defects and localized non-uniformities in HgCdTe materials and devices used for infrared photovoltaic arrays. To further the development of a quantitative working model for LBIC, this paper focuses on the application of the technique to photovoltaic structures that are represented by a discrete element equivalent circuit. For this particular case the LBIC signal arises due to the lateral photovoltaic effect in non-uniformly illuminated open-circuit photodiodes. The outcomes of the model predict all of the experimentally observed geometrical features of the LBIC image and signal. Furthermore, the model indicates that the LBIC signal has an extremely weak dependence on the p-n junction reverse saturation current, and shows a linear dependence with laser power. This latter feature map be useful for non-contact measurement of the quantum efficiency of individual photodiodes within a large two-dimensional focal plane array. The decay of the LBIC signal outside the physical boundary of the p-n junction is of the same form as the roll-off in the short circuit photoresponse and, therefore, can be used to extract the diffusion length of minority carriers. Experimental data is obtained from an arsenic implanted p-on-n junction fabricated on MBE grown Hg/sub 1-x/Cd/sub x/Te material with an x-value of 0.3. The p-on-n diode is shown to be uniform and of high quality with an R/sub 0/A product of 1/spl times/10/sup 8/ /spl Omega//spl middot/cm/sup 2/ at 77 K. The validity of the simple model developed in this paper, is confirmed by the excellent agreement with experimental results. Consequently, the LBIC technique is shown to be an appropriate diagnostic tool for non-contact quantitative analysis of semiconductor materials and devices.<>     

Interpretation of current flow in photodiode structures using laser beam-induced current for characterization and diagnostics

This paper presents an interpretation of the physical mechanisms involved in the generation of laser beam-induced current (LBIC) in semiconductor p-n junction diodes. LBIC is a nondestructive semiconductor characterization technique that has been used in a qualitative manner for a number of years and is especially useful for examining individual photodiodes within large two-dimensional arrays of devices. The main thrust of this work is the analysis of LBIC in terms of nonzero steady-state circulatory current flow within the device and, hence, the interpretation of LBIC line profiles to diagnose the patterns of current flow within the structure. This provides an important basis for future studies seeking to relate LBIC to indicators of p-n junction performance and integrity such as dark current components and reverse bias saturation current. In particular, this paper examines the ideal cases of a single isolated p-n junction diode structure, and also considers an array of such devices in close proximity to each other. Modifications to the idealized theory that are required to account for localized junction leakage and surface recombination are presented, and the effect of Schottky contacts is discussed. Numerical simulations based on the HgCdTe family of semiconductors are presented to support the theory.     

Correlation of laser-beam-induced current with current-voltage measurements in HgCdTe photodiodes

Laser-beam-induced current (LBIC) is being investigated as an alternative to electrical measurements of individual photodiodes in a two-dimensional array. This is possible because LBIC only requires two electrical contacts to an array and the two-dimensional scanning of a focused laser beam across the array to image the entire array. The measured LBIC profiles, obtained from linear arrays of HgCdTe photodiodes, will be used to study the uniformity of photodiodes in the array and to extract the R₀A of the photodiodes. It will be shown that the shape of the LBIC signal is correlated to the electrical performance of the photodiode, with R₀A related to the spreading length of the photodiodes. Linear arrays of n-on-p, mid-wavelength infrared (MWIR) and long wave-length infrared (LWIR) devices were formed in liquid-phase epitaxy HgCdTe epilayers using a plasma junction-formation technique. The LBIC profiles were measured on each of the devices at various temperatures. For the MWIR devices, the extracted spreading length shows no correlation with R₀A. However, the LBIC signal does detect nonuniform devices within the array. For the case of the LWIR devices, the spreading length is extracted as a function of temperature, with the R₀A subsequently calculated from the spreading length. The calculated R₀A, obtained without requiring contact to each photodiode in the array, agrees well with electrical measurements. Asymmetry of the LBIC signals for certain devices in the arrays is shown to be a result of localized leakage at the photodiode junction or from the contact pads through the passivation layers. These results are confirmed by numerical modeling of the device structures.     

Monolithically integrated HgCdTe focal plane arrays

The cost and performance of hybrid HgCdTe infrared (IR) focal plane arrays are constrained by the necessity of fabricating the detector arrays on a CdZnTe substrate. These substrates are expensive, fragile, available only in small rectangular formats, and are not a good thermal expansion match to the silicon readout integrated circuit. We discuss in this paper an IR sensor technology based on monolithically integrated IR focal plane arrays that could replace the conventional hybrid focal plane array technology. We have investigated the critical issues related to the growth of HgCdTe on Si read-out integrated circuits and the fabrication of monolithic focal plane arrays: (1) the design of Si read-out integrated circuits and focal plane array layouts; (2) the low-temperature cleaning of Si(001) wafers; (3) the growth of CdTe and HgCdTe layers on read-out integrated circuits; (4) diode creation, delineation, electrical, and interconnection; and (4) demonstration of high yield photovoltaic operation without limitation from earlier preprocessing such as substrate cleaning, molecular beam epitaxy (MBE) growth, and device fabrication. Crystallographic, optical, and electrical properties of the grown layers will be presented. Electrical properties for diodes fabricated on misoriented Si and readout integrated circuit (ROIC) substrates will be discussed. The fabrication of arrays with demonstrated I–V properties show that monolithic integration of HgCdTe-based IR focal plane arrays on Si read-out integrated circuits is feasible and could be implemented in the third generation of IR systems.     

激光束诱导电流在HgCdTe双色探测器工艺检测中的应用

报道了激光束诱导电流（LBIC）在碲镉汞（HgCdTe）红外双色探测器工艺检测中的应用.通过LBIC测试,发现p型HgCdTe材料由B＋离子注入损伤形成的n区面积大于其注入面积,并获得n区横向的精确分布.同时,运用LBIC,获得了p型HgCdTe材料因不同能量的等离子体干法刻蚀诱导的刻蚀台面侧壁工艺损伤形成的n区横向分布,并得到了n区横向宽度与等离子体能量的关系.     

Junction depth measurement in HgCdTe using laser beam induced current (LBIC)

A new, nondestructive junction depth measurement technique for HgCdTe photovoltaic devices is investigated. The technique uses a scanning laser microscope to obtain laser beam induced current (LBIC) data from which information regarding the junction depth is extracted, and is applicable to both homojunction and heterojunction diodes. For implanted heterojunction photodiodes, the position of the n-p junction relative to the heterojunction is an important factor determining completed device performance, with blind photodiodes resulting if the n-p junction is incorrectly placed. At present, the only methods available for junction depth determination (e.g., secondary ion mass spectroscopy and differential Hall) are destructive and not applicable as routine process monitoring techniques. It is envisaged that the development of a nondestructive routine process monitoring procedure will help improve yield and reduce the cost of HgCdTe photovoltaic devices. In this paper, experimental and theoretical results are presented in order to assess the sensitivity of the new technique to the effects of junction doping density, illumination wavelength, frontside/backside illumination, and test structure geometry.     

12.5 μm长线列碲镉汞焦平面杜瓦组件

256×2碲镉汞焦平面模块由2个256×1元芯片和2个光伏信号硅读出电路模块平行对称组成,并分别与2个不同波段的微型滤光片以架桥式结构直接耦合后封装在全金属微型杜瓦内,形成了长波256×2长线列碲镉汞红外探测器件组件。基本解决了256×2焦平面杜瓦组件的关键技术,即高精度的组装技术、器件在冷平台上的热失配设计技术和高可靠性封装技术。对抑制杂散光、降低背景辐射、提高组件的可靠性等方面采取了一系列措施,使研制的碲镉汞焦平面器件获得了良好的性能,并进行了一系列空间适应性实验,实验前后的组件性能未发生明显变化,满足工程化应用的要求。     

Investigation of the cross-hatch pattern and localized defects in epitaxial HgCdTe

The cross-hatch pattern in epitaxial HgCdTe layers grown by Hg-melt LPE on (111) CdZnTe substrates has been investigated by several means including x-ray topography. Whenever present, the pattern is detectable by x-ray, being aligned along the 〈110〉 directions in the surface plane with a spacing of about 100 to 200 μm. A surface-relief manifestation of the cross hatch, however, exhibits the same orientation but with a smaller spacing. A surface pattern having only 10 nm of relief was found by optical profilometry mapping. Misfit dislocations are displaced from the layer/substrate interface and appear to follow the same symmetry but do not have the same spacing as the other features. The mechanisms interrelating the cross-hatch phenomena and connecting them to cross hatches in detector array performance are difficult to identify. In addition, an array of photovoltaic LWIR HgCdTe detectors in MBE-grown HgCdTe was examined in detail according to a failure analysis protocol, in order to characterize the material defects and correlate them with pixels that have higher than normal leakage current. Large, medium, and small morphological defects, were seen before and after decorative etching. The large kind are most likely the funnel-shaped “void” defects, and are accompanied by several dislocations. About 63% of the failed diodes contained observable material defects.     

长波光导HgCdTe探测器的输运特性

测量了长波光导ＨｇＣｄＴｅ线列探测器在１．２～３００Ｋ的电阻率－温度（Ｒ－Ｔ）特性，结果表明：高性能和低性能探测元的Ｒ－Ｔ特性明显不同，前者有与正常ＨｇＣｄＴｅ材料Ｒ－Ｔ关系相似的变化规律，后者则与简并ＨｇＣｄＴｅ材料相似．探测器的性能与最大电阻温度有对应关系     

HgCdTe器件中pn结结区扩展的表征方法

报道了液氮温度下激光束诱导电流(LBIC)和I-V测试两种在HgCdTe器件中pn结结区扩展的表征方法.通过LBIC和I-V测试,发现了p型HgCdTe材料中由B+离子注入成结和干法刻蚀成结对材料造成的损伤使得有效结区范围大于注入和刻蚀面积,并获得n区横向扩展.同时,通过对比,相互印证两种方法得到的测试结果一致.