空间遥感用近红外InGaAs焦平面组件

介绍了InGaAs PIN探测器的结构和主要性能指标,综述了InGaAs探测器的研究进展,特别是我国空间遥感用高均匀性长线列InGaAs焦平面组件的关键技术和主要性能结果.近年来,我国空间遥感用InGaAs得到了较快发展,研制出光谱响应为0.9～1.7μm的正照射和背照射256×1元InGaAs线列焦平面组件,室温下其峰值响应率分别为7.8×1011cm·Hz1/2/W和4.5×1011 cm·Hz1/2/W,而且利用正照射256×1元InGaAs线列焦平面组件实现了扫描成像,图像清晰.此外,研制了光谱响应延展至2.4μm的256×1元InGaAs线列平面组件,其室温下峰值探测率为2.5×1010cm·Hz1/2/W.这些研究结果为下一步更长线列焦平面组件的研制提供了坚实的基础,同时器件的性能需要进一步提高,以满足空间遥感应用的要求.     

InGaAs近红外线列焦面阵的研制进展

研制出光谱响应为0.9～1.7μm的256×1、512×1元InGaAs线列焦平面组件,和光谱响应延展至2.4μm的256×1元InGaAs线列焦平面组件.焦平面组件包括光敏芯片、读出电路、热电制冷器以及管壳封装.光敏芯片在Inp/InGaAs/InP(p-i-n)双异质结外延材料上采用台面结构实现,并与128×1或512×1元CTIA结构的读出电路耦合.焦平面器件置于双列直插金属管壳中,采用平行缝焊的方式进行封装.介绍了高均匀性长线列InGaAs焦平面组件的关键技术和主要性能结果,为更长线列焦平面组件的研制提供了坚实的基础.     

近红外256×1元InGaAs焦平面探测器无效像元研究

采用分子束外延方法生长的PIN型InP/InGaAs/InP双异质结材料制备了正照射256×1元近红外探测器,并与128×1奇偶两路读出电路互连,制备了近红外256×1元焦平面探测器.针对近红外InGaAs焦平面探测器中的无效像元问题,通过光学显微镜、扫描电镜和电学测试将无效像元进行分类,并分析了无效像元产生的原因.研...     

基于N-on-P结构的背照射延伸波长640×1线列InGaAs探测器

在N-on-P型In0.78Al0.22As/In0.78Ga0.22As外延材料上,采用感应耦合等离子体(ICP)刻蚀技术制备了背照射640×1线列InGaAs探测器芯片,研究了探测器光电性能.结果表明,室温下单元器件响应截止波长和峰值波长分别为2.36μm和1.92μm,平均优值因子(R0A)为16.0Ω.cm2,峰值量子效率达到了37.5%;在1 ms积分时间下焦平面探测器平均峰值探测率达到了2.01×1011 cmHz1/2/W,响应非均匀性为8.77%,盲元率约为0.6%.     

短波红外InGaAs焦平面探测器研究进展

短波红外InGaAs焦平面探测器具有探测率高、均匀性好等优点,在航天遥感、微光夜视、医疗诊断等领域具有广泛应用。近十年来,中国科学院上海技术物理研究所围绕高灵敏度常规波长（0.9～1.7 μm） InGaAs焦平面、延伸波长（1.0～2.5 μm） InGaAs焦平面以及新型多功能InGaAs探测器取得了良好进展。在常规波长InGaAs焦平面方面,从256×1、512×1元等线列向320×256、640×512、4 000×128、1 280×1 024元等多种规格面阵方面发展,室温暗电流密度优于5 nA/cm2,室温峰值探测率优于5×1012 cm·Hz1/2/W。在延伸波长InGaAs探测器方面,发展了高光谱高帧频1 024×256、1 024×512元焦平面,暗电流密度优于10 nA/cm2和峰值探测率优于5×1011 cm·Hz1/2/W@200 K。在新型多功能InGaAs探测器方面,发展了一种可见近红外响应的InGaAs探测器,通过具有阻挡层结构的新型外延材料和片上集成微纳陷光结构,实现0.4～1.7 μm宽谱段响应,研制的320×256、640×512焦平面组件的量子效率达到40%@0.5 m、80%@0.8 m、90%@1.55 m;发展了片上集成亚波长金属光栅的InGaAs偏振探测器,其在0 °、45 °、90 °、135 °的消光比优于20:1。     

320 × 256 InGaAs短波红外焦平面阵列探测器

研制了320×256 InGaAs焦平面阵列(FPA)探测器,它由InGaAs光电二极管阵列(PDA)与Si CMOS集成读出电路(ROIC)通过In凸点倒焊技术混合集成。背照射工作方式下其响应光谱范围为0.9~1.7μm。为实现InGaAs PDA与所设计的可调积分电容跨阻抗反馈放大器接口电路良好匹配,分析讨论了InGaAs光电二极管响应度、暗电流、结电容等光电特性对表征InGaAs FPA的主要性能指标的影响,优化了InGaAs光电二极管单元结构设计。采用优化结果研制的320×256 InGaAs FPA,在室温下的峰值探测率达到6×1012cm.Hz1/2.W-1,动态范围达到68 dB。     

2560×2048元短波红外InGaAs焦平面探测器（特邀）

高性能大规模小像元短波红外InGaAs焦平面探测器是新一代航天遥感仪器向高空间分辨率、高能量分辨率、高时间分辨率发展需要的核心器件。文中报道了高密度InGaAs探测器阵列设计与制备,并与匹配的Si-CMOS读出电路倒焊互连形成焦平面的最新研究进展,重点突破了高密度小像素探测器的暗电流和噪声抑制、百万像素焦平面倒焊互连等关键技术,解决了高平整度芯片面形控制、In柱凸点形貌和高度一致性控制、高密度倒焊偏移控制等倒焊新工艺,研制了像元中心距10 μm的2560×2048元焦平面探测器,其峰值探测率优于1.0×1013 cm·Hz1/2/W,响应不均匀性优于3%,有效像元率优于99.7%,动态范围优于120 dB。采用该焦平面进行了实验室演示成像,图片清晰。     

2~3微米波段InP基无锑激光器和光电探测器

介绍了我们基于InP衬底采用无锑材料体系开展的2~3μm波段激光器及光电探测器方面的持续探索,包括采用赝配三角形量子阱方案的2~2.5μm波段I型InGaAs多量子阱激光器、采用虚拟衬底异变方案的2.5~3μm波段I型InAs多量子阱激光器、以及截止波长大于1.7μm的高In组分InGaAs光电探测器等,这些器件结构均采用GSMBE方法生长,其中2.5μm以下波长的激光器已实现了高于室温的CW激射并获实际应用,2.9μm波长的激光器也在热电制冷温度下实现了脉冲激射,含超晶格电子阻挡势垒层的截止波长2.6μm InGaAs光电探测器暗电流显著减小,此类光电探测器材料已用于航天遥感焦平面组件的研制.     

短波红外InGaAs焦平面噪声特性

为研究铟镓砷焦平面的噪声特性,设计了两种不同吸收层掺杂浓度的InGaAs外延材料,采用标准工艺制备了平面型160×128元光敏芯片,并与相同结构的读出电路倒焊耦合形成160×128元焦平面,采用改变积分时间和改变器件温度的方法,测试焦平面的信号与噪声.通过研究不同材料参数、器件性能与焦平面噪声的关系,定量分析了短波红外InGaAs焦平面的噪声特性.结果表明,焦平面噪声主要来源于焦平面耦合噪声和探测器噪声,降低InGaAs外延材料吸收层的掺杂浓度,可以有效降低探测器电容,从而降低焦平面的耦合噪声;而探测器噪声由探测器暗电流和工作温度影响,该噪声在长积分时间下决定了焦平面的总噪声水平.实现低暗电流、低电容特性的光敏芯片是降低焦平面噪声的有效途径.     

128x128元InAs/GaSb II类超晶格红外焦平面探测器

报道了128×128元InAs/GaSb Ⅱ类超晶格红外焦平面阵列探测器的研究成果.实验采用分子束外延技术在GaSb衬底上生长超晶格材料.红外吸收区结构为13 ML(InAs)/9 ML(GaSb),器件采用PIN结构,焦平面阵列光敏元大小为40μm×40μm.通过台面形成、侧边钝化和金属电极生长,以及与读出电路互连等工艺,得到了128×128面阵长波焦平面探测器.在77 K时测试,器件的100%截止波长为8μm,峰值探测率6.0×109cmHz1/2W-1.经红外焦平面成像测试,探测器可得到较为清晰的成像.     

9μm截止波长128×128 AlGaAs/GaAs量子阱红外焦平面探测器阵列

报道了128×128 AlGaAs/GaAs量子阱红外焦平面探测器阵列的设计和制作.采用金属有机化学气相淀积外延技术生长外延材料,并在GaAs集成电路工艺线上完成工艺制作.为得到器件参数,设计制作了台面尺寸为300μm×300μm的大面积测试器件;77K下2V偏压时暗电流密度为1.5×10-3A/cm2;80K工作温度下,器件峰值响应波长为8.4μm,截止波长为9μm,黑体探测率DB 为3.95×108(cm·Hz1/2)/W.将128×128元 AlGaAs/GaAs量子阱红外焦平面探测器阵列芯片与相关CMOS读出电路芯片倒装焊互连,在80K工作温度下实现了室温环境目标的红外热成像,盲元率小于1%.     

High Conversion Efficiency InP/InGaAs Strained Quantum Well Infrared Photodetector Focal Plane Array With 9.7 $mu$m Cut-Off for High-Speed Thermal Imaging

InP/InGaAs material system is an alternative to AlGaAs/GaAs for long wavelength quantum well infrared photodetectors (QWIPs). We demonstrate a large format (640 $times$ 512) QWIP focal plane array (FPA) constructed with the strained InP/InGaAs material system. The strain introduced to the structure through utilization of $hbox{In}_{0.48}hbox{Ga}_{0.52}hbox{As}$ (instead of $hbox{In}_{0.53}hbox{Ga}_{0.47}hbox{As}$ ) as the quantum well material shifts the cut-off wavelength from $sim$8.5 to 9.7 $muhbox{m}$. The FPA fabricated with the 40-well epilayer structure yields a peak quantum efficiency as high as 12% with a broad spectral response $(Deltalambda/lambda_{rm p}=17%)$. The peak responsivity of the FPA pixels is 1.4 A/W corresponding to 20% conversion efficiency in the bias region where the detectivity is reasonably high ($2.6times 10^{10} hbox{cmHz}^{1/2}/hbox{W}$ , f/1.5, 65 K). The FPA providing a background limited performance temperature higher than 65 K (f/1.5) satisfies the requirements of most low integration time/low background applications where AlGaAs/GaAs QWIPs suffer from read-out circuit noise limited sensitivity due to lower conversion efficiencies. Noise equivalent temperature differences of the FPA are as low as 19 and 40 mK with integration times as short as 1.8 ms and 430 $muhbox{s}$ (f/1.5, 65 K).      

Large Format AlInAs–InGaAs Quantum-Well Infrared Photodetector Focal Plane Array For Midwavelength Infrared Thermal Imaging

We report the first large format (640times512) AlInAs-InGaAs quantum-well infrared photodetector (QWIP) focal plane array (FPA), and investigate the characteristics of AlInAs-InGaAs QWIPs both at pixel and FPA level. The measurements on the detectors fabricated with molecular beam epitaxy grown epilayer structure including 30 InGaAs quantum wells (26 Aring thick, N_D=2times10¹⁸ cm^-3) yielded very promising characteristics. The detectors with lambda_p=4.2 mum and Deltalambda/lambda_p=25% displayed a background-limited performance temperature as high as 105 K with f/2 aperture. The noise equivalent temperature difference of the FPA is as low as 23 mK (f/1.5) at 105-K sensor temperature with 99.6% operability. These results are comparable to the best results reported for AlGaAs-InGaAs midwavelength infrared QWIPs showing the promise of this material system for completely lattice-matched multiband QWIP FPAs.     

High-Temperature Tunneling Quantum-Dot Intersublevel Detectors for Mid-Infrared to Terahertz Frequencies

Quantum-dot infrared photodetectors have emerged as attractive devices for sensing long wavelength radiation. Their principle of operation is based on absorption of radiation via intersublevel transitions in quantum dots. Multiple layers of self-organized ln(Ga)As/Ga(Al)As quantum dots are generally incorporated in the active region of these devices. Three-dimensional quantum confinement allows normal incidence operation. This paper describes a novel variation in the design of these devices which allows a significant reduction of the dark current, high temperature operation and extension of operation to terahertz frequencies. The principle of operation and operating characteristics of this device - the tunnel quantum-dot intersublevel detector - are described. Operation is demonstrated from 6-80 mum at temperatures up to 300 K with acceptable values of peak responsivity (0.1-0.75 A/W) and specific detectivity (10⁷-10¹¹cm ldr Hz^1/2/W^-1 , depending on temperature and wavelength).     

High average and high peak brightness slab laser

A high average and high peak brightness Nd:YAG MOPA laser system composed of a laser-diode-pumped Nd:YAG master oscillator, flash-lamp-pumped slab power amplifiers and a phase conjugated mirror was developed. The system demonstrates an average output power of 235 W at a repetition rate of 320 Hz and a peak power of 30 MW at a pulse duration of 24 ns with M²=1.5. Both an average brightness of 7×10⁹ W/cm²·sr and a peak brightness of 1×10¹⁵ W/cm2·sr are achieved simultaneously. The system design rules that we confirmed suggest that by replacing lamp pumping in the amplifier with laser-diode pumping, an average output power of ~1 kW can be obtained at ~1 kHz with a higher average brightness of ~3×10¹⁰ W/cm²·sr and a higher peak brightness of ~3×10¹⁵ W/cm²·sr     

Diode-pumped ytterbium-doped Sr5(PO4)3F laser performance

The performance of the first diode-pumped Yb³⁺-doped Sr ₅(PO₄)₃F (Yb:S-FAP) solid-state laser is discussed. An InGaAs diode array has been fabricated that has suitable specifications for pumping a 3×3×30 mm Yb:S-FAP rod. The saturation fluence for diode pumping was deduced to be 5.5 J/cm ² for the particular 2.8 kW peak power diode array utilized in our studies. This is 2.5× higher than the intrinsic 2.2 J/cm ² saturation fluence as is attributed to the 6.5 nm bandwidth of our diode pump array. The small signal gain is consistent with the previously measured emission cross section of 6.0×10^-20 cm², obtained from a narrowband-laser pumped gain experiment. Up to 1.7 J/cm³ of stored energy density was achieved in a 6×6×44 mm Yb:S-FAP amplifier rod. In a free running configuration, diode-pumped slope efficiencies up to 43% (laser output energy/absorbed pump energy) were observed with output energies up to ~0.5 J per 1 ms pulse. When the rod was mounted in a copper block for cooling, 13 W of average power was produced with power supply limited operation at 70 Hz with 500 μs pulses     

640 × 512 Pixels Long-Wavelength Infrared (LWIR) Quantum-Dot Infrared Photodetector (QDIP) Imaging Focal Plane Array

Epitaxially grown self-assembled InAs-InGaAs-GaAs quantum dots (QDs) are exploited for the development of large-format long-wavelength infrared focal plane arrays (FPAs). The dot-in-a-well (DWELL) structures were experimentally shown to absorb both 45deg and normal incident light, therefore, a reflection grating structure was used to enhance the quantum efficiency. The devices exhibit peak responsivity out to 8.1 mum, with peak detectivity reaching ~1times10¹⁰ Jones at 77 K. The devices were fabricated into the first long-wavelength 640times512 pixel QD infrared photodetector imaging FPA, which has produced excellent infrared imagery with noise equivalent temperature difference of 40 mK at 60-K operating temperature     

320×256 GaAs/AlGaAs长波红外量子阱焦平面探测器

量子阱红外探测器(Quantum well infrared photodetector, QWIP)已经经历了20多年的深入研究,各种QWIP器件,包括量子阱红外探测器焦平面阵列(FPA)的研制也已经相当成熟。但是在国内,受制于整体工业水平, QWIP焦平面阵列器件的研制仍然处于起步阶段。研制了基于GaAs/ AlxGa1-xAs 材料、峰值响应波长为9.9 m的长波320256 n型QWIP焦平面阵列器件,其像元中心距25 m, 光敏元面积为22 m22 m。GaAs衬底减薄后的QWIP焦平面阵列,与Si基CMOS读出电路(ROIC)通过铟柱倒焊互连,并且在65 K工作温度下进行了室温环境目标成像。该焦平面器件的规模和成像质量相比之前国内报道的结果都有较大提高。焦平面平均峰值探测率达1.51010 cmHz1/2/W。     

长波红外2048元线列碲镉汞焦平面器件

介绍了长波红外2048元线列碲镉汞焦平面器件的制备技术和达到的性能参数.探测器采用离子注入平面pn结制备光敏元,通过间接倒焊技术和读出电路互联,采用8个256元焦平面模块拼接2048元线列焦平面器件.光敏元的响应截止波长达到9.9μm,相应的RoA达到10Ωcm2,平均峰值探测率达到9.3×1010cmHz1/2 W-1,响应不均匀性为8%,有效光敏元率大干99.5%.