量子级联红外探测器

半导体基中远红外探测器在成像、传感、国家安全以及国防领域具有广泛的应用背景.目前,在这个领域最主流的技术之一是量子阱红外探测器( QWIPs).传统的量子阱红外探测器往往存在较大的暗电流和较低的工作温度等限制.量子级联探测器( QCDs)是一种新型的光伏型量子阱红外探测器.其工作原理基于电子吸收光子后在量子阱的子带间跃...     

GaN基量子阱红外探测器的设计

为了实现GaN基量子阱红外探测器,利用自洽的薛定谔一泊松方法对GaN基多量子阱结构的能带结构进行了研究。考虑了GaN基材料中的自发极化和压电极化效应,通过设计适当的量子阱结构,利用自发极化和压电极化的互补作用,设计出了极化匹配的GaN基量子阱红外探测器,为下一步实现GaN基量子阱红外探测器做好了准备。     

GaN基多量子阱红外探测器研究进展（特邀）

多量子阱红外探测器是一种新型的利用子带跃迁机制的探测器件,具有非常高的设计自由度。GaN/Al(Ga)N量子阱由于大的导带带阶,超快的电子驰豫时间,超宽的红外透明区域以及高的声子能量,使得其成为继GaAs量子阱红外探测器之后又一潜在的探测材料结构。文中详细综述了国内外关于GaN基量子阱红外子带吸收及其探测器件的研究进展。首先介绍了量子阱红外探测器的工作原理及其选择定则,接着从极性GaN基多量子阱、非极性或半极性GaN基多量子阱以及纳米线结构GaN基多量子阱三个方面回顾当前GaN基多量子阱红外吸收的一些重要研究进展,包括了从近红外到远红外甚至太赫兹波段范围的各种突破。最后回顾了GaN基多量子阱红外探测器件的研究进展,包括其光电响应特性和高频响应特性,并对其未来的发展进行总结和展望。     

8～12μm超晶格量子阱红外探测材料与器件的新进展

超晶格材料与量子阱器件的发展提供了一条实现8～12μm红外探测的新途径，作者曾分绍过GaAs-GaAlAs n型光导多量子阱红外探测器、InAsSb和InAs-Ga1-xInxSb应变超晶格材料和器件及HgTe-CdTe超晶格材料，本文将补充GaAs-GaAlAs p型光导多量子阱和光伏(或称Kastalsky)型红外探测器；以GaAs或InGaAs为基极的红外热电子晶体管(IHET)；Ga1-xAlxSbAlGb超晶格材料和GexSi1-x-Si量子阱材料与内光电子发射红外探测器。这些都是目前研制长波红外材料与器件的热点。     

超晶格和量子阱红外探测器研究进展

本文综述了超晶格和量子阱红外探测器的发展。文章简要地阐明了超晶格和量子阱的原理,详细地介绍了业已发展的各种超晶格和量子阱红外探测器的原理、结构和性能等。还介绍了几种最有希望用于探测器制造的超晶格材料。     

非均匀GaAs/AlGaAs量子阱红外探测器材料表征和器件性能研究

本文利用分子束外延（MBE）技术成功生长了GaAs/AlGaAs非均匀量子阱红外探测器材料,并对相关微结构作了细致表征。分析比较了非均匀量子阱结构和常规量子阱红外探测器性能差异,并对比研究了不同势阱宽度下非均匀量子阱红外探测器的性能变化。通过高分辨透射电子显微镜（HRTEM）结合能谱仪（EDS）对非均匀量子阱红外探测器材料微结构进行了分析,并利用二次离子质谱仪（SIMS）对非均匀势阱掺杂进行了表征。结果表明,该量子阱外延材料晶体质量很好,量子阱结构和掺杂浓度也与设计值符合较好。对于非均匀量子阱红外探测器,通过改变每个阱的掺杂浓度和势垒宽度,可以改变量子阱电场分布,而与传统的均匀量子阱红外探测器相比,其暗电流显著下降（约一个数量级）。在不同阱宽下,非均匀量子阱的跃迁模式发生改变,束缚态到准束缚态跃迁模式下（B-QB）的器件具有较高的黑体响应率以及较低的暗电流。     

国外量子阱红外焦平面探测器的发展概况

以GaAs/A1GaAs为代表的Ⅲ-Ⅴ量子阱红外焦平面探测器因其成熟的材料生长和器件工艺技术,一直是与传统的HgCdTe红外探测器并驾齐驱的红外探测器.近十年来随着对器件结构、机理及器件工艺的不断改进,大面阵Ⅲ-Ⅴ量子阱红外焦平面器件发展显著.本文介绍了量子阱红外焦平面探测器的优越性及存在的问题,当前欧美国家量子阱红外焦平面探测器的最新研究发展、产品现状及应用前景.     

量子阱红外探测器双面金属光栅设计优化

提出了一种增强量子阱红外探测器耦合效率的双面金属光栅结构。采用三维时域有限差分算法（3D-FDTD）对GaAs/AlGaAs 量子阱红外探测器双面结构金属光栅进行了仿真分析。通过对比不同周期、占空比、金属层厚度结构参数下探测器的电场分布及相对耦合效率,确定了4.8 m 探测器优化的双面金属光栅结构。与顶部和底部单层金属光栅结构比较,双面金属光栅结构探测器相对耦合效率提高到3 倍以上。探测器相对耦合效率随光栅周期变化的双峰曲线特性体现了双面金属光栅结构在双色量子阱红外探测器光耦合方面的潜力。同时该结构还可以应用于单色、双色及多色量子阱焦平面红外探测器。     

局域光场增强的量子阱红外探测器（特邀）

量子阱红外探测器是继碲镉汞红外探测器之后又一重要的可以在中、长波段和甚长波段工作的红外探测器件。它在长波红外探测、多色探测及其焦平面技术方面表现出比碲镉汞红外探测器更具特色的优势,对量子阱红外探测器的研究将在很大程度上推动我国红外探测器技术的发展。这一探测器的突出优势是其材料均匀性好,制备技术成熟。但是由于量子效率偏低,且无法直接吸收垂直入射红外光,所以需要针对不同的红外探测波段,设计和制备各类光栅或微腔结构来进行光耦合及局域光场增强以有效提升探测器性能。如何更有效提升量子阱红外探测器的光耦合效率,降低暗电流,提高器件工作温度是仍然是目前研究的重点。文中着重介绍和总结了近5年来研究的局域光场增强的新型量子阱红外探测器,从提高探测器光耦合效率、降低器件暗电流和提高工作温度等方面重点讨论各种量子阱红外探测器的新结构和新机理,同时展望了这一探测器的未来发展方向。     

GaAs/Al_xGa_(1-x)As量子阱红外探测器光谱特性的研究

采用MBE法制备了不同结构参数及不同阱中掺杂浓度的GaAs/AlxGa1-xAs量子阱红外探测器外延材料。通过对量子阱红外探测器材料特性和器件特性的实验测试及理论分析,研究了量子阱红外探测器的响应光谱特性,并通过薛定谔方程和泊松方程的求解,对掺杂对量子阱能级的影响做了研究。结果表明,由于应力导致的能带非抛物线性使得阱中能级发生了变化,从而引起吸收峰向高能方向发生了漂移,而阱中进行适度的掺杂没有对量子阱能级造成影响,光致发光谱实验结果与之吻合较好。在光电流谱的实验分析基础之上,分析了量子阱阱宽、Al组分与峰值探测波长λ的关系,为量子阱红外探测器的设计优化提供了参考。     

光导管暗电阻时间漂移特性的动态补偿

为了消除光导管暗电阻时间漂移特性对测量结果造成的影响,提出了一种动态补偿方法。将该方法应用于对红外水分仪中PbS光导管的输出信号进行即时修正,较好地克服了PbS光导管暗电阻时间漂移特性的影响。本文所介绍的动态补偿法,原理简单易行,对提高检测系统的稳定性和精确度具有明显的技术应用价值。     

A solid-state infrared image converter

A photoconductor-electroluminescent type infrared image converter panel has been studied through the application of doped CdSe photoconductive powder layers of different thickness to the earlier type of image converter and through temperature operation. The spectral sensitivity extended from 0.7 to 1.2 µm with sensitivity peak at 0.9 µm and the minimum detectable input power density reached approximately 2×10^-10W/cm²for 0.9 µm at 0°C. Projected infrared images are converted to visible electroluminescent images with a resolution of 3 to 8 TV lines/mm and a response time of an order of 1 to 10^-2s, depending upon the photoconductor thickness and the operating temperature. The converter panel may be used as a night vision panel with an additional infrared source. This paper describes a preparation of doped CdSe photoconductor suitable for a photoconductor-electroluminescent device, some of its properties, and the effect of the photoconductor thickness and of the operating temperature on the performance of the solid-state infrared image converter. Converted visible images using experimental panels are also shown.     

Monolithic integrated waveguide photodetector

An InGaAs photodetector for detection in the 1.0?1.5?m wavelength range has been integrated at the end of and above a ridge waveguide in InP. The waveguides were in n?-InP/n+-InP and had an average propagation loss of 3dB/cm at 1.15?m. The reflection losses were 3dB and the coupling loss was 2dB. The photodetector was an InGaAs photoconductor lattice-matched to InP and exhibited a bias-dependent optical gain of up to 2.5 with a unity-gain quantum efficiency of 49% at 1.15?m. 25% of the guided light was absorbed by the photoconductor. The speed of the photoconductor was found to be bias-dependent, varying from 10 ns to 150 ns rise/fall times.     

Fast,Air‐Stable Infrared Photodetectors based on Spray‐Deposited Aqueous HgTe Quantum Dots

The ability to detect near‐infrared and mid‐infrared radiation has spawned great interest in colloidal HgTe quantum dots (QDs). In contrast to the studies focused on extending the spectral range of HgTe QD devices, the temporal response, another figure of merit for photodetectors, is rarely investigated. In this work, a single layer, aqueous HgTe QD based photoconductor structure with very fast temporal response (up to 1 MHz 3 dB bandwidth) is demonstrated. The device is fabricated using a simple spray‐coating process and shows excellent stability in ambient conditions. The origin of the remarkably fast time response is investigated by combining light intensity‐dependent transient photocurrent, temperature‐dependent photocurrent, and field‐effect transistor (FET) measurements. The charge carrier mobility, as well as the energy levels and carrier lifetimes associated with the trap states in the QDs, are identified. The results suggest that the temporal response is dominated by a fast bimolecular recombination process under high light intensity and by a trap‐mediated recombination process at low light intensity. Interestingly, it was found that the gain and time response of aqueous HgTe QD‐based photoconductors can be tuned by controlling the QD size and surface chemistry, which provides a versatile approach to optimize the photodetectors with selectable sensitivity and operation bandwidth.     

A solid-state image converter

AnEL-PCimage converter has been designed to convert the near-IR radiation obtained from light-emitting semiconductor diodes into visible radiation. In addition to wavelength conversion, a quantum gain was also obtained. High contrast ratios are shown to be dependent upon photoconductor capacitance. Concentric, noncoplanar electrode structures have been utilized to achieve photoconductor capacitance values several orders of magnitude smaller than those of a correspondingELelement. Data are shown describing the intensifier operation as a function of applied voltage and frequency. The input-output transfer function shows operation over three orders of magnitude of input intensity. Peak optical gains of 150 are reported.     

P型掺杂区工艺对Si基Pinned型光电二极管量子效率的影响

为了更全面、系统地分析Si基Pinned型光电二极管(PPD,pinned photodiode)量子效率的工艺敏感特性,基于考虑表面(SRH,shockley-read -hall)复合率模型的时域有限差分数值模拟方法,对不同P⁺型表面层和P型外延(EPI,e pi taxial)层工艺条件下PPD可见光谱量子效率的变化特征及物理机制进行了研究。结果表明 ,P⁺型表面层离子束注入剂量和注入能量的增加分别引起非平衡载流子SRH复合率升高和 PPD势垒区顶部下移,均可导致低于500nm波段量子效率的衰减,而 后者进一步引起的势垒区纵向宽度缩 减使该影响可持续至650nm波段;P型EPI掺杂浓度增加引起PPD势垒 区底部上移,导致500～750nm 波段量子效率的衰减;P型EPI厚度增加引起衬底强SRH复合区光电荷比重降低,导致高于700 nm波段量 子效率得到提升并趋向饱和。通过分析发现,Si基材料中光子吸收深度对波长的强依赖关系 是导致两种P型 掺杂区工艺条件对量子效率存在波段差异性影响的根本原因。     

Microwave signal-to-noise performance of CdSe bulk photoconductive detectors

The microwave signal and noise response of CdSe bulk photoconductive detectors have been measured and compared with that of a high-speed junction photodiode. The signal measurements were made with CW intensity modulated light at 3000 Mc. Excellent quantitative agreement was obtained between the simple photoconductivity theory of direct light demodulation and experiment. At low optical intensities, the observed noise can be accounted for within the framework of existing theories of generation-recombination (GR) noise when the effects of electron retrapping are accounted for. At high optical intensities, nonlinear deviations are observed which can be accounted for only qualitatively. The results demonstrate clearly that such a photoconductor, when used as a simple quantum counter, will always be thermal rather than GR noise limited. Measurements show that the photoconductor as it is usually used in a nonoptimum configuration is some 50 db less sensitive than a good photodiode.     

基于单片机的智能机器人的设计

本设计以8051单片机系列家族中的AT89S52为主芯片,进行数据的处理与系统的控制;该系统集成了红外发射接收探头、红外遥控接收器、光敏电阻和声音传感器等信号检测装置,驱动电机正反转的动作执行机构LG9110,以及LED、蜂鸣器等输出器件,从而实现了循迹、避障、避崖、光控、声控和状态显示等功能,达到机器人系统开发的丰富...     

Demodulation of low-level broad-band optical signals with semiconductors: Part II—Analysis of the photoconductive detector

A fast response photoconductor with a high frequency bias supply is considered as an envelope detector for optical signals. The sensitivity is studied and compared with that of the diode demodulator. The ratio of SNR for the two devices is equal to the photocurrent gain. It is shown to be theoretically possible to achieve enough current gain to overcome the noise of the following amplifier. The current gain comes from two effects. One is a true photocurrent gain in the semiconductor itself, which can exceed unity if the microwave field reverses before the photocarriers are swept out. It can be as high as the number of times the photocarriers traverse the photoconductor before they recombine. The impedance transformation from the high resistance of the detector to the amplifier input gives additional current gain. Analysis of gain-bandwidth limitations reveals no restriction imposed by material parameters, in contrast to the case of dc bias. With RF bias, blocking contacts to the crystal are useable and the relationship between material resistivity and gain-bandwidth avoided. The limiting parameters are the signal bandwidth and the bias supply frequency, the device current gain being limited to the square of the Q value of the circuit. The effect of G-R noise is also considered and conditions derived under which it is unimportant. The two cases of a photoconductor in a rectangular waveguide and in a cavity are studied in more detail, and design equations relating sensitivity to the material and to the circuit parameters are deduced. For bandwidths up to at least 1 kMc, the photoconductor in the cavity can greatly outperform the photodiode. Its sensitivity can approach that of the photomultiplier with a high efficiency cathode, which opens the possibility of extending this high performance into the infrared.     

I–V and Differential Conduction Characteristics of an AlGaAs/GaAs Lateral Quantum Dot Infrared Photodetector

A new infrared detector design, henceforth referred to as a lateral quantum dot infrared photodetector (LQDIP), with the potential for a tunable internal spectral response was investigated. In this design, InAs quantum dots are buried in a GaAs quantum well, which is in turn tunnel-coupled to a second GaAs quantum well. Photoexcited electrons from the quantum dots are expected to tunnel over to the second well, where they are then swept out via a lateral (perpendicular to the growth direction) bias voltage. The lateral photocurrent is in part directed to tunnel into the second quantum well by the depletion field of a narrow pinch-off gate, applied vertically (parallel to the growth direction). Under a proper biasing arrangement, this detector architecture is expected to exhibit the ability to tune to select infrared frequencies as well as operate with reduced dark currents and unity gain in the second well. The LQDIP detector architecture, operating principles and conditions, and preliminary results of I–V, photocurrent, and differential conductance measurements are all discussed.