Very long wavelength infrared focal plane arrays with 50% cutoff wavelength based on type-Ⅱ In As/GaSb superlattice

A very long wavelength infrared（VLWIR） focal plane array based on In As/Ga Sb type-Ⅱ super-lattices is demonstrated on a Ga Sb substrate. A hetero-structure photodiode was grown with a 50% cut-off wavelength of 15.2 μm, at 77 K.A 320×256 VLWIR focal plane array with this design was fabricated and characterized. The peak quantum efficiency without an antireflective coating was 25.74% at the reverse bias voltage of-20 mV, yielding a peak specific detectivity of 5.89×10^10cm·Hz^1/2·W^-1. The operability and the uniformity of response were 89% and 83.17%. The noise-equivalent temperature difference at 65 K exhibited a minimum at 21.4 mK, corresponding to an average value of 56.3 mK.

Thermal and mechanical characterizations of a substrate-free focal plane array

We propose a substrate-free focal plane array （FPA） and the microcantilevers extend from a supporting frame. in this paper. The solid substrate is completely removed, Using finite element analysis, the thermal and mechanical characterizations of the substrate-free FPA are presented. Because of the large decrease in thermal conductance, the supporting frame is temperature dependent, which brings out a unique feature： the lower the thermal conductance of the supporting frame is, the higher the energy conversion efficiency in the substrate-free FPA will be. The results from the finite element analyses are consistent with our measurements： two types of substrate-free FPAs with pixel sizes of 200×200 and 60×60 um^2 are implemented in the proposed infrared detector. The noise equivalent temperature difference （NETD） values are experimentally measured to be 520 and 300 mK respectively. Further refinements are considered in various aspects, and the substrate-free FPA with a pixel size of 30×30 um^2 has a potential of achieving an NETD value of 10 mK.

Progress in quantum well and quantum cascade infrared photodetectors in SITP

This paper presents a review of recent advances in quantum well and quantum cascade infrared photodetectors developed in Shanghai Institute of Technical Physics, Chinese Academy of Sciences(SITP/CAS). Firstly, the temperature-and bias-dependent photocurrent spectra of very long wavelength(VLW) GaAs/AlGaAs quantum well infrared photodetectors(QWIPs) are studied using spectroscopic measurements and corresponding theoretical calculations in detail. We confirm that the first excited state, which belongs to the quasi-bound state, can be converted into a quasi-continuum state induced by bias and temperature. Aided by band structure calculations, we propose a model of the double excited states that determine the working mechanism in VLW QWIPs. Secondly, we present an overview of a VLW QWIP focal plane array(FPA)with 320×256 pixels based on the bound to quasi-bound(BTQB) design. The technology of the manufacturing FPA based on the QWIP structures has been demonstrated. At the operating temperature of 45 K, the detectivity of QWIP FPA is larger than 1.4×10^(10) cm·Hz^(1/2)/W with a cutoff wavelength larger than 16 μm. Finally, to meet the needs of space applications, we proposed a new long wavelength quantum cascade detector with a broadband detection ranging from 7.6 μm to 10.4 μm. With a pair of identical coupled quantum wells separated by a thin barrier, acting as absorption regions, the relative linewidth(?E/E) of response can be dramatically broadened to 30.7%. It is shown that the spectral shape and linewidth can be tuned by the thickness of the thin barrier, while it is insensitive to the working temperature. The device can work above liquid nitrogen temperature with a peak responsivity of 63 mA/W and Johnson noise limited detectivity of 5.1×10~9 cm·Hz^(1/2)/W.

Growth and fabrication of a mid-wavelength infrared focal plane array based on type-II InAs/GaSb superlattices

We present the fabrication of a mid-wavelength infrared focal plane array （FPA） based on type-II InAs/GaSb strain layer superlattices （SLs）. The detectors contain a 400-period 8 ML InAs/8 ML GaSb SL active layer, which is grown by solid source molecular beam epitaxy on GaSb （100） N type substrates. Lattice mismatch between the superlattices and GaSb substrate achieves 148.9 ppm. The full width at half maximum of the first or- der satellite peak from X-ray diffraction was 28 arcsec. Single element detectors and FPA with a 128 x 128 pixels were fabricated using citric acid based solution wet chemical etching. Chemical and physical passivation effectively reduces the surface leakage and this process was characterized by I-V measurement. The devices showed a 50% cut-off wavelength of 4.73 μm at 77 K. The photodiode exhibited an RoA of 103 f2. cm2. The FPA was characterized with an integration time of 0.5 ms and F/2.0 optics at 77 K and the average blackbody detectivity of the detectors is 2.01 × 10^9 cm.Hz^1/2/W.

New CMOS readout circuit with background suppression and CDS for infrared focal plane array applications

A high injection, large dynamic range, stable detector bias, small area and low power consumption CMOS readout circuit with background current suppression and correlated double sampling (CDS) for a high-resolution infrared focal plane array applications is proposed. The detector bias error in this structure is less than 0.1 mV. The input resistance is ideally zero, which is important to obtain high injection efficiency. Unit-cell occupies 10 μm× 15 μm area and consumes less than 0.4 mW power. Charge storage capacity is 3 × 108 electrons. The function and performance of the proposed readout circuit have been verified by experimental results.

A novel MEMS-based focal plane array for infrared imaging

On the basis of opto-mechanical effect and micro electromechanical system(MEMS)technology,a novel substrate-free focal plane array(FPA)with the thermal isolated structure for uncooled infrared imaging is developed,even as alternate evaporated Au on SiN cantilever is used for thermal isolation.A human thermal image is obtained successfully by using the infrared imaging system composed of the FPA and optical detecting system.The experiment results show that the realization of thermal isolation structure in substrate-free FPA increases the temperature rise of the deflecting leg effectively,whereas the noise equivalent temperature difference(NETD)is about 200 mK.

New Dynamic Algorithm for IRFPA Bad Pixel Detection and Compensation Based on Statistics

Based on the analysis to the behavior of bad pixels, a statistics-based auto-detecting and compensation algorithm for bad pixels is proposed. The correcting process is divided into two stages： bad pixel detection and bad pixel compensation. The proposed detection algorithm is a combination of median filtering and statistic method. Single frame median filtering is used to locate approximate map, then statistic method and threshold value is used to get the accurate location map of bad pixels. When the bad pixel detection is done, neighboring pixel replacement algorithm is used to compensate them in real-time. The effectiveness of this approach is test- ed by applying it to I-IgCATe infrared video. Experiments on real infrared imaging sequences demonstrate that the proposed algorithm requires only a few frames to obtain high quality corrections. It is easy to combine with traditional static methods, update the pre-defined location map in real-time.

Adaptive nonuniformity correction for IRFPA sensors based on neural network framework

For infrared focal plane graded during signal acquisition array sensors, imagery is departicularly nonuniformity. In this paper, an adaptive nonuniformity correction technique is proposed which simultaneously estimates detector-level and readout- channel-level correction parameters using neural network approaches. Firstly, an improved neural network framework is designed to compute the desired output. Secondly, an adaptive learning rate rule is used in the gain and offset parameter estimation process. Experimental results show the proposed algorithm can achieve a faster convergence speed and better stability, remove nonuniformity and track parameters drift effectively, and present a good adaptability to scene changes and nonuniformity conditions.

NEW DARK CURRENT SUPPRESSION CMOS READOUT CIRCUIT WITH NOVEL CDS STRUCTURE FOR LARGE FORMAT QWIP FPA

A new Dark Current Suppression (DCS) CMOS readout circuits for large format Quantum-Well-Infrared Photo-detector (QWIP) Focal-Plane-Array (FPA) with novel CorrelatedDouble-Sampling (CDS) structure based on dynamic source-follower are proposed, which can overcome the drawbacks of the present techniques, such as sensitive to the non-uniformity of the QWIP materials, poor readout noise features, low frame frequency, limited injection efficiency and dynamic range, etc. The dummy is adopted to realize dark current suppression, while the integration time. Through the novel CDS structure, the output waveform is boxcar, and the frame frequency is increased. Simulation results demonstrate that, in high background sense, the proposed DCS circuit can suppress the dark current, achieve good readout performance, such as low power consumption, high charge sensitivity, high resolution, large dynamic range, and insensitive to the non-uniformity of the QWIP materials.

国外凝视型舰载红外搜索与跟踪系统综述

为一种被动式告警系统,舰载红外搜索与跟踪系统(IRST)能够可探测和跟踪掠海反舰导弹和低空威胁目标,为舰船作战管理系统和指挥控制系统提供目标指示信息,在提高舰船的态势告警能力和自防御能力方面具有不可替代的优势。与传统的360°机械扫描的IRST系统相比较,新型的凝视型IRST系统使用多个基于FPA阵列凝视非转动传感器组件,增大俯仰角覆盖,具有的高数据更新率确保快速反应时间,增强了对高速低探测性目标以及非对称威胁目标的自动探测和跟踪性能。论文介绍国外新型凝视型舰载红外搜索与跟踪系统的发展现状、技术特点和应用,对重点技术进行了分析。

A substrate-free optical readout focal plane array with a heat sink structure

A substrate-ffee optical readout focal plane array （FPA） operating in 8-12 um with a heat sink structure （HSS） was fabricated and its performance was tested. The temperature distribution of the FPA with an HSS investigated by using a commercial FLIR IR camera shows excellent uniformity. The thermal cross-talk effect existing in traditional substrate-free FPAs was eliminated effectively. The heat sink is fabricated successfully by electroplating copper, which provides high thermal capacity and high thermal conductivity, on the frame of substrate-free FPA. The FPA was tested in the optical-readout system, the results show that the response and NETD are 13.6 grey/K （F / # = 0.8） and 588 inK, respectively.

大面阵中波红外连续变焦光学系统设计

针对制冷式大面阵640×512凝视焦平面阵列探测器,设计了一套中波红外连续变焦光学系统。该系统由变焦系统和二次成像系统构成,包括7片透镜和2个反射镜组成的折叠光路。首先,根据变焦原理和专业光学设计软件给出了系统结构及其参数。然后,分析了系统的像质和冷反射效应。最后,验证了系统的性能指标。结果表明:该系统可以实现50～500mm的连续变焦,变焦过程中目标景物始终清晰可见;系统在耐奎斯特频率处的全视场光学传递函数大于0.35,全视场畸变小于2%,无冷反射现象;具有分辨率高、热灵敏度高、像质好、变焦轨迹平滑等特点,基本满足设计要求。

星载长波红外焦平面成像系统

随着国产红外焦平面技术的发展,使用长波红外焦平面器件采用推扫方式对地观测的成像系统成为现实。文中介绍的星载长波红外焦平面成像系统是一个工作波段在8.0~12.5μm之间的对地观测相机,该相机采用两条256×1的长波红外焦平面探测器,60 K的深低温斯特林制冷机和同轴两反RC主光学系统的技术方案,通过设置合理的探测器冷屏、并采用-26°C的低温光学系统以及高性能的信息获取和处理电路,系统获得了较好的温度灵敏度,利用该相机获取了外景长波红外图像,这是我国利用国产的红外焦平面器件获取的截止波长大于12.5μm的红外图像。

大视场大相对孔径长波红外物镜

介绍适用于非致冷焦平面阵列 (FPA)探测器的大视场大相对孔径长波红外物镜设计与研制 由三块非球面锗透镜组成 ,采用”负 正 正”像方远心光路 ,全视场角和相对孔径分别达 135°和F/ 0 .8 镜头的成像性能接近于衍射受限 ,具有体积小、重量轻、像面辐照度均匀等优点 给出非球面锗透镜的研制。

边积分边读出低噪声红外焦平面读出电路研究

设计了一款低噪声InGaAs焦平面读出电路.提出一种新型相关双采样电路结构,可在边积分边读出模式下有效抑制积分电容(0.15 pF)的KTC噪声.电路经0.5μm 5 V Nwell CMOS工艺流片,测试结果符合设计目标,在高帧频边积分边读出模式下工作状态良好,电路噪声约1.7×10-4 V,动态范围大于80 dB.

快速制冷型红外焦平面成像制导系统设计

红外焦平面成像技术是一种通过摄取景物热辐射分布,并将其转换为人眼可见图像的技术,广泛应用于侦察、制导、空间探测等方面.针对红外制导小体积、快速启动的应用要求,设计了快速启动红外焦平面成像制导系统.对应用于系统的折反式红外镜头、快速启动型红外焦平面探测器、低噪声成像电路等进行了设计,设计结果满足制导条件下的红外成像要求.

环孔工艺的碲镉汞长波红外576×6焦平面探测器组件

碲镉汞长波红外576×6焦平面探测器组件是高性能热像仪的核心组件.本文中作者完成了碲镉汞长波红外576×6焦平面探测器组件的设计,利用环孔技术制备出576×6焦平面探测器芯片,经过杜瓦封装、配斯特林制冷机后成为实用的探测器组件.性能参数测试表明:典型的探测率达到1.79×1011cm Hz1/2/W,非均匀性达到14.6%,盲元率达到6.0%,并完成探测器组件的实验室演示成像.

Ⅲ-Ⅴ族半导体全(多)光谱焦平面探测器新进展

近年来,经济社会和武器装备的信息化对半导体光电子学器件提出了更高的要求,无论是国防还是民用工程都需要有自己的关键器件。光电探测器组件作为关键器件之一,世界各国都给予了高度重视,也取得了很大的进展。文中主要介绍了Ⅲ"Ⅴ族半导体全(多)光谱焦平面探测器的研究进展情况,包括量子阱红外探测器(QWIP)、AlGaN紫外焦平面探测器、InGaAs近红外室温焦平面探测器和Sb化物焦平面探测器等。

InSb红外焦平面探测器现状与进展

红外焦平面探测器技术是一种通过摄取景物热辐射分布图像,并将其转换为人眼可见图像的技术。近年来红外探测器技术发展迅速,在军事、工业、农业、医学等各领域显示出越来越重要的应用。本文对锑化铟红外焦平面探测器的应用及发展情况进行了分析,并对其发展前景进行了展望。

利用傅里叶变换测量红外焦平面器件响应光谱

利用傅里叶变换测量光谱的方法具有大通量、高信噪比的优势,在红外测试领域具有重要的应用价值。利用步进扫描和时间分辨的方法,可以同步傅里叶变换红外光谱仪动镜移动和焦平面器件的输出,获得高质量的干涉图,从而计算得到器件的响应光谱。在本系统测量范围400~10000 cm-1内,所得光谱的分辨率可以达到4 cm-1。