红外目标探测器的特征及其军用前景

论述了中波和长波红外探测器的特征及装备前景;机载前视红外（ＦＬＩＲ）成像系统用于地面目标探测和机载红外搜索跟踪（ＩＲＳＴ）系统用于空中目标探测的前景。     

A detailed calculation of the auger lifetime in p-type HgCdTe

There has been recent experimental evidence that showed, in heavily doped p-type HgCdTe, the lifetime may be limited by the Auger 7 recombination mechanism. We have performed a detailed calculation of both the Auger 7 and Auger 1 lifetimes as a function of Cd composition (x), temperature (T), and doping (N_A). Compared with those done 20 years ago, the depth and breadth of these calculations result in a significant increase in the accuracy of the predictions. We present here the Auguer 7 lifetime for two different compositions, x=0.305 and x=0.226 over a range of temperature extending from 60 K to 300 K and for acceptor doping from 10¹⁵ cm⁻³ to 10¹⁸ cm⁻³. The calculated results for MWIR (x=0.305) are in reasonably good agreement with recent experiments performed on MWIR HgCdTe at 77 K over a range of doping. In addition, we calculated γ (≡ τ_A7 /τ_A1) with the same doping, composition (x ≈ 0.22), for a range of temperatures (40–80 K) and found γ=3–6.     

Composition and thickness control of thin LPE HgCdTe layers using x-ray diffraction

Double-axis x-ray rocking curve measurements have been used to nondestructively characterize the composition profile of HgCdTe heterojunction photodiode structures grown by liquid phase epitaxy (LPE). In particular, the thickness and composition profile of the thin graded-composition cap layer are determined through an empirical correlation between rocking curve parameters and composition profiles measured by SIMS. Spatial maps of cap layer thickness and composition are generated from automated measurements of x-ray rocking curves across a wafer. X-ray mapping has been instrumental in improving the spatial uniformity of cap layers and in maintaining control of the growth process in Hg-rich LPE dipping reactors.     

Molecular beam epitaxial growth of HgCdTe on CdZnTe(311)B

A series of n-type, indium-doped Hg_1−xCd_xTe (x∼0.225) layers were grown on Cd_0.96Zn_0.04Te(311)B substrates by molecular beam epitaxy (MBE). The Cd_0.96Zn_0.04Te(311)B substrates (2 cm × 3 cm) were prepared in this laboratory by the horizontal Bridgman method using double-zone-refined 6N source materials. The Hg_1−xCd_xTe(311)B epitaxial films were examined by optical microscopy, defect etching, and Hall measurements. Preliminary results indicate that the n-type Hg_1−xCd_xTe(311)B and Hg_1−xCd_xTe(211)B films (x ∼ 0.225) grown by MBE have comparable morphological, structural, and electrical quality, with the best 77 K Hall mobility being 112,000 cm²/V·sec at carrier concentration of 1.9×10⁺¹⁵ cm⁻³.     

低耦合损耗的光电混合光纤旋转连接器

设计了一种光电混合光纤旋转连接器,能实现相对旋转的光信号在较大对准误差范围内低损耗连接.旋转状态下的自聚焦透镜准直光纤输出的光信号,并由PIN光电探测器将其转换为电信号,冉由激光器根据电信号再生出原始光信号继续在光纤通讯系统中传输.该光电混合光纤旋转连接器在离轴偏移量至520μm或对准倾斜角至0.5°时的附加耦合损耗为0.3 dB,而采用双自聚焦透镜的光纤旋转连接器要获得小于3 dB的插入损耗,其离轴偏移或倾斜角度必须小于100 μm和0.10°相比之下,本文设计的光纤旋转连接器能降低系统对机械加上及装配精度的要求,具有较高的实用价值.     

Modeling of LWIR HgCdTe Auger-Suppressed Infrared Photodiodes under Nonequilibrium Operation

The general approach and effects of nonequilibrium operation of Auger-suppressed HgCdTe infrared photodiodes are well understood. However, the complex relationships of carrier generation and dependencies on nonuniform carrier profiles in the device prevent the development of simplistic analytical device models with acceptable accuracy. In this work, finite element methods are used to obtain self-consistent steady-state solutions of Poisson’s equation and the carrier continuity equations. Experimental current–voltage characteristics between 120 K and 300 K of HgCdTe Auger-suppressed photodiodes with cutoff wavelength of λ _c = 10 μm at 120 K are fitted using our numerical model. Based on this fitting, we study the lifetime in the absorber region, extract the current mechanisms limiting the dark current in these photodiodes, and discuss design and fabrication considerations in order to optimize future HgCdTe Auger-suppressed photodiodes.     

Morphology of Inductively Coupled Plasma Processed HgCdTe Surfaces

Inductively coupled plasma (ICP) processing has become the industrial processing standard for HgCdTe and its related II–VI compounds. In this study ICP processes were developed that allow several microns of HgCdTe to be plasma etched while maintaining a low root-mean-square (RMS) roughness, and even improving the surface roughness in the case of HgCdTe-on-Si. These ICP processes are superior to older electron cyclotron resonance (ECR) plasma etches. The resulting ICP plasma processed surfaces are oxygen and carbon free, have a good reflection high-energy electron diffraction (RHEED) pattern, and have only a small amount of mercury depletion, x = 0.22 to 0.47 (where x is the ratio of Cd to␣Hg), in the first 25 ? to 30 ? of the HgCdTe. Nanofeatures of the as-grown HgCdTe are retained during the process and are believed to be indicative of the fundamental defect mechanisms in the different HgCdTe etched surfaces. Results from these experiments strongly suggest that ICP plasma processes can be used to delineate pixels, etch vias, clean surfaces, and even produce epi-ready surfaces that would allow HgCdTe to become much more manufacturable, and perhaps allow the replacement of wet processing in HgCdTe.     

热探测器温度对非制冷红外热像仪测温的影响

根据红外辐射理论和热像仪测温原理,给出了热探测器非制冷红外热像仪的温度计算公式;针对热探测器热像仪,分析了探头温度对热像仪测量结果的影响.     

A comparative study and performance characteristics of ion-implanted and heterojunction short-wave infrared HgCdTe focal-plane arrays

Short-wave infrared (SWIR) HgCdTe focal-plane arrays (FPAs) with a cutoff wavelength of 2.5 μm have been produced using both planar ion-implanted and heterojunction-mesa device structures. The two-dimesnional FPAs are comprised of a 320×256 format with 30-μm pixel pitch and are cooled by a multistage thermo-electric (TE) cooler. Measured R₀A values of the two types of device structures show similar results below about 130 K because of the performance-limiting effect of the surface passivation of the heterojunction. However, a substantial difference is seen above 130 K and up to 300 K between the two structures types, with the heterojunction-mesa p-on-n device having an order of magnitude higher R₀A value than the planar ion-implanted n-on-p configuration. The difference in the R₀A values is reflected in the FPA images of the two different device types, where at 200 K, both FPAs display a clear picture with the n-on-p implanted device having a somewhat lesser resolution. However, no image can be seen from the planar-implanted FPA at 300 K, whereas the heterojunction-mesa FPA still exhibits a notable image at this temperature. These differences are examined and are attributed largely to higher diffusion and generation-recombination (g-r) currents that are thought to be prevalent in the ion-implanted n-on-p device structure. Yet, baking studies carried out show the ion-implanted diodes to be slightly more robust, as experiments reveal that they tend to survive a 120°C heat treatment longer than the mesa devices, which tend to degrade after a certain period of time. The nature of n-type donors in ion-implanted diodes is discussed, and a new theory based on Te antisites is proposed to explain recent experimental findings.     

Development of a high-selectivity process for electron cyclotron resonance plasma etching of II-VI semiconductors

The erosion rate of resist during electron cyclotron resonance (ECR) plasma etching of II-VI semiconductors is the limiting factor for the selectivity (values range from 5:1 to 10:1). We have measured the erosion rates of AZ 1529, a commercially available diazonaphthoquinone (DNQ) novolak photoresist, under plasma conditions optimized for etching of the underlying semiconductor and have developed an in-situ technique to “harden” the resist by exposing it to an argon-only ECR plasma. A subsequent standard plasma process can then be used to etch the II-VI material, thereby achieving selectivity values greater than 50:1.