碲镉汞高温中波红外探测器的制备研究

采用CdTe/ZnS双层钝化工艺制备了640×512@15 μm碲镉汞中波探测器。研究了退火温度对CdTe/MCT界面及CdTe钝化膜质量的影响。经测试表明:本公司制备的碲镉汞HOT中波探测器可以在125 K稳定工作,但与国外的先进技术相比仍存在差距,需要在MCT材料改进和器件加工工艺上继续深入研究,才能提高探测器的工作温度和稳定性。     

甚长波碲镉汞红外探测器制备研究

报道了碲镉汞甚长波红外焦平面探测器的最新研究进展。采用水平液相外延In掺杂和垂直液相外延Ａs掺杂技术生长了高质量的p on n型双层异质结材料。并通过提高材料质量将双层异质结材料的双晶衍射半峰宽控制在30 arcsec以内。基于台面器件加工、表侧壁钝化以及In柱互连工艺,制备了640×512,25μm碲镉汞甚长波红外焦平面器件。通过进一步优化了材料生长和芯片制备工艺,在65 K的工作温度下,该器件的截止波长为1435 μｍ,有效像元率为9806,平均峰值探测率为809×1010cm·Hz1/2·W-1。     

长波红外碲镉汞探测器

1 引言 红外辐射最早是1800年英国的天文学家赫谢耳(W.Herschel)在研究太阳光谱的热效应时,用水银温度计测量各种颜色光的加热效果而发现的。1830年,L.Nobili利用塞贝克发现的温差电效应制成了“温差电型辐射探测器”;     

碲镉汞探测器的表面钝化

讨论表面钝化的概念、特性和作用,比较各类钝化技术及用于碲镉汞红外探测器的适应性.     

碲镉汞长波光导红外探测器的侧面钝化研究

为了解决小光敏元器件由于裸露在外的侧面占的比例大,易发生Hg溢出,对器件性能影响大的问题,在芯片制备过程中采用先刻蚀图形,再进行表面和侧面阳极氧化的工艺,制备了器件.利用SEM对芯片的侧面钝化效果进行了表征,并对器件进行了真空热浸和紫外光照射实验.SEM分析表明,器件侧面明显变光滑,通过腐蚀和侧面钝化,可以有效去除离子束刻蚀引入的缺陷.真空热浸的实验结果表明,侧面钝化后,器件耐热浸能力变强,小面积器件尤为明显.紫外光照射实验结果表明,经紫外光照射后,常规和侧面钝化器件性能均有所提高,这是因为紫外光照射促进了氧的扩散,减少了由于氧不足造成的氧的空位;同时,臭氧和氧原子的强氧化作用引起侧面的氧化.这些结果可为侧面钝化在短波红外半导体器件方面的应用提供实验基础.     

CdTe/ZnS复合钝化层对长波碲镉汞器件性能的影响研究

采用CdTe/ZnS复合钝化技术对长波HgCdTe薄膜进行表面钝化,并对钝化膜生长工艺进行了改进。采用不同钝化工艺分别制备了MIS器件和二极管器件,并进行了SEM、C-V和I-V表征分析,研究了HgCdTe/钝化层之间的界面特性及其对器件性能的影响。结果表明,钝化工艺改进后所生长的CdTe薄膜更为致密且无大的孔洞,CdTe/HgCdTe界面晶格结构有序度获得改善;采用改进的钝化工艺制备的MIS器件C-V测试曲线呈现高频特性,界面固定电荷面密度从改进前的1.671011 cm-2下降至5.691010 cm-2;采用常规钝化工艺制备的二极管器件在较高反向偏压下出现较大的表面沟道漏电流,新工艺制备的器件表面漏电现象获得了有效抑制。     

双层异质结碲镉汞甚长波红外焦平面探测器研究进展

报道了甚长波碲镉汞红外焦平面探测器的最新研究进展。采用水平液相外延In掺杂和垂直液相外延As掺杂技术生长p-on-n异质结材料,并基于湿法腐蚀、表侧壁钝化、In柱互连工艺,制备了第一支甚长波碲镉汞台面型焦平面器件。在60 K的工作温度下,该器件的截止波长达到14.28 μm,有效像元率为94.5%,平均峰值探测率达到8.98×10¹⁰ cm·Hz^1/2·W^-1。     

碲镉汞表面钝化研究进展

碲镉汞(MCT)红外探测器近些年的发展非常迅速。随着相关技术的不断进步,对探测器的要求也越来越高。MCT探测器的表面对杂质、缺陷、损伤、温度等因素非常敏感,而器件的很多性能直接由其表面的性质决定,因此MCT材料表面的钝化被看成是红外探测器制备的关键工艺之一。为了提高器件表面的稳定性,最常用的方法就是对MCT材料表面进行钝化处理。主要介绍了几种常见的MCT材料表面钝化方法,然后结合国内外文献重点介绍了常见的介质膜钝化方法,并对以后的工作进行了展望。     

甚长波碲镉汞红外探测器的发展

天基红外技术对于远程弹道导弹防御具有重要作用.当飞来的导弹位于地球阴影区域时,作为背阳的结果,空间温度很低,导弹呈现为一个微弱的冷目标,峰值波长在甚长波红外(VLWIR,大于14μm)波段,这时就需要VLWIR探测器.VLWIR对于大面阵碲镉汞焦平面(FPA)器件的设计来说是一种非常具有挑战性的波段.它要求高均匀性、低缺陷率、高量子效率、低暗电流和低噪声.主要通过对近年来刊发的部分有关英语文献资料的归纳分析,介绍了有关VLWIR/MCT技术的发展状况,其中一个发展趋势是从n-on-p空位掺杂器件结构转向非本征掺杂p-on-n器件结构.     

A CdTe passivation process for long wavelength infrared HgCdTe photo-detectors

Passivant-Hg_1−xCd_xTe interface has been studied for the CdTe and anodic oxide (AO) passivants. The former passivation process yields five times lower surface recombination velocity than the latter process. Temperature dependence of surface recombination velocity of the CdTe/n-HgCdTe and AO/n-HgCdTe interface is analyzed. Activation energy of the surface traps for CdTe and AO-passivated wafers are estimated to be in the range of 7–10 meV. These levels are understood to be arising from Hg vacancies at the HgCdTe surface. Fixed charge density for CdTe/n-HgCdTe interface measured by CV technique is 5×10¹⁰ cm⁻², which is comparable to the epitaxially grown CdTe films. An order of magnitude improvement in responsivity and a factor of 4 increase in specific detectivity (D*) is achieved by CdTe passivation over AO passivation. This study has been conducted on photoconductive detectors to qualify the CdTe passivation process, with an ultimate aim to use it for the passivation of p-on-n and n-on-p HgCdTe photodiodes.     

Au／CdTe＋ZnS／HgCdTe双层介质膜MIS器件的制备及研究

通过介质膜ZnS、CdTe薄膜材料的Ar^ 束溅射沉积研究,结合HgCdTe器件工艺,成功制备了以ZnS、CdTe双层介质膜为绝缘层的HgCdTe MIS器件;通过对器件的C－V特性实验分析,获得了CdTe/HgCdTe界面电学特性参数。实验表明：溅射沉积介质膜CdTe ZnS对HgCdTe的表面钝化已经可以满足HgCdTe红外焦麦面器件表面钝化的各项要求。     

Metalorganic chemical vapor deposition CdTe passivation of HgCdTe

CdTe epilayers are grown by metalorganic chemical vapor deposition (MOCVD) on bulk HgCdTe crystals with x ~ 0.22 grown by the traveling heater method (THM). The THM HgCdTe substrates are (111) oriented and the CdTe is grown on the Te face. The metalorganic sources are DMCd and DETe, and the growth is performed at subatmospheric pressure. Ultraviolet (UV) photon-assisted hydrogen radicals pretreatment plays a dominant role in the electrical properties of the resulting heterostructures. The requirements of a good passivation for HgCdTe photodiodes vis-a-vis the passivation features of CdTe/HgCdTe heterostructures are discussed. The effect of valence band offset and interface charges on the band diagrams of p-isotype CdTe/HgCdTe heterostructures, for typical doping levels of the bulk HgCdTe substrates and the MOCVD grown CdTe, is presented. Electrical properties of the CdTe/HgCdTe passivation are determined by capacitance-voltage and current-voltage characteristics of metal-insulator-semiconductor test devices, where the MOCVD CdTe is the insulator. It is found that the HgCdTe surface is strongly inverted and the interface charge density is of the order of 10¹²cm² when the CdTe epilayer is grown without the UV pretreatment. With the in-situ UV photon-assisted hydrogen radicals pretreatment, the HgCdTe surface is accumulated and the interface charge density is -4. 10¹¹ cm^-2.     

Characterization of CdTe for HgCdTe surface passivation

The objectives of this work are to study the physical and chemical structure of CdTe films using secondary ion mass spectrometry (SIMS) and atomic force miroscopy (AFM) and to demonstrate the usefulness of these analytical techniques in determining the characteristics of CdTe-passivation films deposited by different techniques on HgCdTe material. Three key aspects of CdTe passivation of HgCdTe are addressed by different analytical tools: a) morphological microstructure of CdTe films examined by atomic force microscopy; b) compositional profile across the interface determined by Matrix (Te)—SIMS technique; c) concentration of various impurities across the CdTe/HgCdTe structure profiled by secondary ion-mass spectrometry.     

Interdiffusion in HgCdTe/CdTe Structures

A method for generating the composition profiles of compound semiconductor multilayer structures while growth and composition dependent interdiffusion are simultaneously occurring is developed. The following composition dependent interdiffusion coefficient for HgCdTe was determined: D_{Hg 1-x}Cd_x(μm²/sec) = 3.15 × 10¹⁰ · 10^3.53x · exp(−2.24 × 10⁴/K) Model profiles compare favorably with experimental profiles for HgCdTe multilayer structures prepared from 180° C to 550° C by VPE, LPE, MOCVD, and UHV methods. At high temperatures, the shape of the experimental profiles are determined by interdiffusion. Because at lower temperatures experimental data is characteristic of the profiling technique, model profiles are convoluted with the resolution of the measurement technique (i.e., scanning and sputter Auger and sputter XPS) to extract the actual profiles from the data.     

Design and development of multicolor MWIR/LWIR and LWIR/VLWIR detector arrays

Multicolor infrared (IR) focal planes are required for high-performance sensor applications. These sensors will require multicolor focal plane arrays (FPAs) that will cover various wavelengths of interest in mid wavelength infrared/long wavelength infrared (MWIR/LWIR) and long wavelength infrared/very long wavelength infrared (LWIR/VLWIR) bands. There has been significant progress in HgCdTe detector technology for multicolor MWIR/LWIR and LWIR/VLWIR FPAs.^1–3 Two-color IR FPAs eliminate the complexity of multiple single-color IR FPAs and provide a significant reduction of weight and power in simpler, reliable, and affordable systems. The complexity of a multicolor IR detector MWIR/LWIR makes the device optimization by trial and error not only impractical but also merely impossible. Too many different geometrical and physical variables need to be considered at the same time. Additionally, material characteristics are only relatively controllable and depend on the process repeatability. In this context, the ability of performing “simulation experiments” where only one or a few parameters are carefully controlled is paramount for a quantum improvement of a new generation of multicolor detectors for various applications.     

Bake stability of CdTe and ZnS on HgCdTe: An x-ray photoelectron spectroscopy study

Mercury cadmium telluride (Hg_1?xCd_xTe or MCT) has been commonly used in devices for infrared (IR) detection. For the optimum performance of the device, a compatible surface-passivation technology that provides long-term stability is required. Using x-ray photoelectron spectroscopy (XPS), the present study examines the effects on Hg_0.8Cd_0.2Te passivated with CdTe and ZnS undergoing baking in vacuum at temperatures typically used for dewar bakeout. Spectra recorded as a function of depth in both cases clearly show out-diffusion of Hg from the substrate toward the surface, even before the bakeout. On baking in vacuum, dramatic changes are observed in the ZnS/MCT case with complete loss of Hg from the sample up to the tested depth of more than 1,000 Å. Compositions of the HgCdTe matrix, formed after Hg out-diffusion, before and after the bakeout are also calculated at selected depths (from 250 Å to 700 Å), which is vital information from a device point of view, as it affects the bandgap of this narrow-band semiconductor.     

Compositionally graded interface for passivation of HgCdTe photodiodes

A compositionally graded CdTe-Hg_1−xCd_xTe interface was created by deposition of CdTe on p-HgCdTe and subsequent annealing. The compositionally graded layer between CdTe and HgCdTe was formed by an interdiffusion process and was used for passivation. The composition gradient (Δx) in the interfacial region and the width of the graded region were tailored by adopting a suitable annealing procedure. The effect of process conditions on the interfacial profile and photoelectric properties such as lifetime and surface recombination velocity was studied in detail. Surface recombination velocity of the p-HgCdTe could be reduced to the level of 3,000 cm/s at 77 K, which represents very good passivation characteristics. The passivation layer formed by this method can be used for the fabrication of high performance and stable modern infrared detectors. Thus, a passivation process is developed, which is simple, effective, reproducible, and compatible with the HgCdTe device fabrication and packaging processes.     

钝化界面植氢优化的碲镉汞中波红外探测芯片

报道了在钝化界面进行低能等离子体植氢优化的n+-on-p碲镉汞(HgCdTe)中波(MW,mid-wavelength)光伏红外探测芯片的研究成果.基于由采用分子束外延技术生长的HgCdTe薄膜材料,通过注入阻挡层的生长、注入窗口的光刻、形成光电二极管的B+注入、钝化介质膜的生长、优化钝化界面的等离子体植氢、金属化和铟...