采用叠盖电极的高性能光导HgCdTe红外探测器

介绍叠盖电极探测器的物理机理和结构，与标准结构探测器比较，其响应率和黑体探测率均有大的增长，实验结果表明响应率增长约１倍，赤体探测率增主３０％。无需改变现有工艺，成功制备实用工程探测器，性能明显提高。     

叠盖电极高性能SPRITE探测器

由于扫出效应，载流子大量聚集在邻近电极的区域，但电极处的强复合作用使SPRITE读出区光生载流子数衰减很多，采用叠盖电极技术可以有效地阻载流子在地电极处的快速复合，读出区中光生非平衡载流子总数为无叠盖电极时的2.18倍，输出信号大幅度提高。该技术对现有工艺的改变极小，是一种比较现实的提高SPRITE探测器性能的有效办法。叠盖电极用于SPRITE探测器，可明显提高性能。     

叠盖电极技术在SPRITE 探测器上的应用

文中主要介绍了叠盖电极技术在SPRITE探测器上的实际应用，并给出了具体实验结果。选择适当的叠盖电极尺寸可以使SPRITE的响应率Rυ提高一倍以上，探测率D^*普遍提高30％左右，高的可达80％。实验结果表明，叠盖电极技术明显地提高了SPRITE器件的性能，是一种简便的提高SPRITE性能的新途径。     

长波光导60元碲镉汞红外探测器通用组件

报道了工程化长波光导６０无碲镉汞红外探测器组件研制的结果，该组件由探测器芯片、杜瓦和制冷器组成。探测器组件的主要指标达到：ＤＢ＝１．７×１Ｏ１０ＣｍＨｚ１／２／ＷＶＢ＝１６×１０４Ｖ／Ｗ。组件的体积小，重量轻，并达到了国军标所规定的红外探测器高、低温实验，温度循环实验，振动实验和冲击等环境实验的要求。     

180元长波碲镉汞线列光导探测器研制

本文报道了长波180元碲镉汞线列光导探测器的初步研制结果,较为详细地介绍了各步探测器制造工艺以及探测器性能的测试结果。最终得到的拼接和单片180元线列器件,其平均峰值探测率D_(xp)~*达2.0×10~(10)cmHz~(1/2)W~(-1),电串音小于5％,功耗小于150mW。     

室温长波光导探测器研究

从理论和实验上详细研究了室温长波HgCdTe光导探测器,提出了室温光导半导体的广义优值,计算了10.6μm HgCdTe探测器的优值和极限性能与组分和掺杂的关系。用HgCdTe外延层制作了光导探测器,描述了它的性能。结果表明10.6μm室温光导探测器的最佳探测率可高于1×10~8cmHz~(1/2)/W,已接近一般的热敏型探测器性能。     

叠盖电极技术在SPRITE 探测器上的应用

文中主要介绍了叠盖电极技术在SPRITE 探测器上的实际应用,并给出了具体实验结 果。选择适当的叠盖电极尺寸可以使SPRITE 的响应率Rv 提高一倍以上,探测率D3 普遍提高30 %左右,高的可达80 %。实验结果表明,叠盖电极技术明显地提高了SPRITE 器件的性能,是一种简便的提高SPRITE 性能的新途径。     

室温长波光导探测器研究

从理论和实验上详细研究了室温长波HgCdTe光导探测器，提出了室温光导半导体的议优值，计算了10．6μmHgCdTe探测器的优值和极限性能与组分和掺杂的关系。用HgCdTe外延层制作了光导探测器，描述了它的性能。结果表明 10．6μm室温光导探测器的最佳探测率可高于1×10^8chHz1/2/W，已接近一般的热敏型探测器性能。     

长波光导HgCdTe探测器芯片钝化研究

在长波光导碲镉汞器件研制过程中，表面钝化是不可缺少的一个重要环节。在早期，表面钝化只进行阳极氧化处理。通过阳极氧化加ＺｎＳ复合钝化实验，得到了比较可靠的表面钝化层，并制造出了高性能、耐高温环境试验的实用化擦探测器芯片，文章对表面钝化层进行了分析。     

Noise Attributes of LWIR HDVIP HgCdTe Detectors

Time series and Fourier-transform data on high-density vertically integrated photodiodes (HDVIP) at 0 and 50 mV reverse bias in the dark have been studied. The detectors have a cutoff wavelength λ _c (60 K) of 10.5 μm. Examination of the detector current time series and Fourier-transform curves of these devices reveals a variety of interesting characteristics: (i) time series displaying switching between four states characteristic of random telegraph signal (RTS) noise, the noise current power spectrum having Lorentzian or double Lorentzian type characteristics, (ii) time series data exhibiting wave-like characteristics with the noise current power spectrum being 1/f ²-like at low frequencies, (iii) time series having a mean value independent of time with the noise current power spectrum being white, and (iv) time series nearly independent of time with the noise current power spectrum having 1/f characteristics. Although from a single array, the excess noise characteristics at low (mHz) frequencies were varied, most of the detectors measured fell into one of these four categories. The predominance of detectors examined had minimal excess low-frequency noise down to ~ 10 mHz. Detectors that displayed RTS noise in reverse bias were repeatable under subsequent measurement. However, when measured at zero bias, the same detectors exhibited no RTS noise, the noise current power spectrum being white in nature.     

LWIR HgCdTe Detectors Grown on Ge Substrates

Long-wavelength infrared (LWIR) HgCdTe p-on-n double-layer heterojunctions (DLHJs) for infrared detector applications have been grown on 100 mm Ge (112) substrates by molecular beam epitaxy (MBE). The objective of this current work was to grow our baseline p-on-n DLHJ detector structure (used earlier on Si substrates) on 100 mm Ge substrates in the 10 μm to 11 μm LWIR spectral region, evaluate the material properties, and obtain some preliminary detector performance data. Material characterization techniques included are X-ray rocking curves, etch pit density (EPD) measurements, compositional uniformity determined from Fourier-transform infrared (FTIR) transmission, and doping concentrations determined from secondary-ion mass spectroscopy (SIMS). Detector properties include resistance-area product (RoA), spectral response, and quantum efficiency. Results of LWIR HgCdTe detectors and test structure arrays (TSA) fabricated on both Ge and silicon (Si) substrates are presented and compared. Material properties demonstrated include X-ray full-width of half-maximum (FWHM) as low as 77 arcsec, typical etch pit densities in mid 10⁶ cm⁻² and wavelength cutoff maximum/minimum variation <2% across the full wafer. Detector characteristics were found to be nearly identical for HgCdTe grown on either Ge or Si substrates.     

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.     

A Novel Stress Characterization Technique for the Development of Low-Stress Ohmic Contacts to HgCdTe

HgCdTe material intended for long-wavelength infrared detection is particularly susceptible to damage from stress. As a result, an ideal ohmic contact needs to have good adhesion and low specific contact resistance. The contact should act as a diffusion barrier and induce the least amount of stress in the underlying material. In this paper we present a set of stress measurements from different ohmic contact materials deposited on short- and long-wavelength HgCdTe films grown by liquid-phase epitaxy (LPE). Using a new experimental technique we remove the substrate and measure the stress induced on single- and multilayered HgCdTe cantilevers. To interpret our results, we develop a theoretical model that describes the physics of elastic deformation in HgCdTe layers. Our model is based on classical thin-plate bending theory and explicitly takes into account the realistic boundary conditions that are present in the experimental setup by using a variational approach.     

Metal-Organic Chemical Vapor Deposition of Hg<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Cd<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Te Fully Doped Heterostructures Without Postgrowth Anneal for Uncooled MWIR and LWIR Detectors

Uncertainty in precursor pulse delays and shapes has been found to be an important factor in Hg_1−x Cd _x Te metal-organic chemical vapor deposition (MOCVD) growth using the interdiffused multilayer process (IMP). Herein, metal-organic concentration changes in the growth zone are examined using an in␣situ infrared (IR) absorption gas monitoring system, and modifications to the interdiffused multilayer process are applied for in␣situ control of stoichiometry, improved morphology, minimized process length, and consumption of precursors. Dimethylcadmium (DMCd) introduction during IMP flush stages in HgTe was used for stoichiometry control. The final stage of heterostructure formation was optimized to prevent Hg outdiffusion. As a result, vacancy concentration was reduced far below the equilibrium level at the growth conditions so the background of n-type doping was revealed. Acceptor doping with arsine (AsH₃) and trisdimethylaminoarsenic (TDMAAs) was examined over a wide range of compositions, and doping levels of 5 × 10¹⁵ cm⁻³ to 5 × 10¹⁷ cm⁻³ were obtained. The presence of both arsenic dopants significantly increased the CdTe growth rate. This caused an increase of Cd mole fraction in the grown material. Doped heterostructures can be grown without any postgrowth anneal and used for mid- and long-wavelength infrared (MWIR and LWIR) devices operating at near-ambient temperatures. Student paper; supervisors are A. Rogalski, J. Piotrowski and J. Szmidt     

混合式长波线列TDI红外探测器改进互连工艺研究

根据目前混合式红外焦平面互连工艺以及对长波线列延时积分红外探测器产量增长的需求,结合现有的工艺设备能力,开发出"共片工艺",以最大限度地提高在互连工艺段的生产效率.     

Status of LWIR HgCdTe-on-Silicon FPA Technology

The use of silicon as an alternative substrate to bulk CdZnTe for epitaxial growth of HgCdTe for infrared detector applications is attractive because of potential cost savings as a result of the large available sizes and the relatively low cost of silicon substrates. However, the potential benefits of silicon as a substrate have been difficult to realize because of the technical challenges of growing low-defect-density HgCdTe on silicon where the lattice mismatch is ∼19%. This is especially true for long-wavelength infrared (LWIR) HgCdTe detectors where the performance can be limited by the high (∼5 × 10⁶ cm⁻²) dislocation density typically found in HgCdTe grown on silicon. The current status of LWIR (9 μm to 11 μm at 78 K) HgCdTe on silicon focal-plane arrays (FPAs) is reviewed. Recent progress is covered including improvements in noise equivalent differential temperature (NEDT) and array operability. NEDT of <25 mK and NEDT operability >99% are highlighted for 640 × 480 pixel, 20-μm-pitch FPAs.     

长波红外偏振图像信息的提取与增强

基于长波红外偏振成像探测技术在目标检测识别领域的优势,本文搭建了长波红外偏振成像探测系统,采集了室内外典型目标的长波红外偏振图像,提取了三类典型目标的斯托克斯矢量、偏振度、偏振角以及两个组合特征δ与ρ等图像信息,并对其特点进行了详细分析。基于对图像偏振信息的解算,提出了一种目标背景对比度增强方法。实验证明该方法可行且有效。     

Electrical Characteristics of PEDOT:PSS Organic Contacts to HgCdTe

The electrical characteristics of organic (3,4-polyethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) contacts to HgCdTe are studied as a potential alternative to metal/HgCdTe contacts. The use of organic PEDOT:PSS contacts offers the potential for an improved contact technology for HgCdTe IR detector arrays. In this work, PEDOT:PSS contacts are deposited on n-type and p-type HgCdTe epilayers by spin coating and patterned using a metal mask. Current-voltage (I-V) characteristics are measured on these contacts, showing nearly ohmic behavior. The temperature dependence of I-V characteristics (T = 40–300 K) shows increased resistance for decreasing temperature, consistent with the temperature dependence of HgCdTe resistivity, suggesting that the I-V characteristics are primarily dominated by the HgCdTe material.