Quantum Well Infrared Photodetectors:the Basic Design and New Research Directions

IntroductionThe physics and applications of quantumwell infrared photodetectors ( QWIP) based onGa As/Al Ga As materials are well established.Thermal infrared( IR) imaging is the main existingapplication of QWIPs fabricated into focal plane...     

多色量子阱红外探测器的发展（上）

军用红外探测器需要使用工作在各种红外波段的大规格,高均匀性多色焦平面阵列器件。满足这些要求的一个候选者就是量子阱红外（光电）探测器（QuantumWell Infrared Photodetector,QWIP）。作为新一代红外探测器,QWIP基于极薄半导体异质结构中的载流子束缚效应。GaAs／A1GaAs／QWIP的主要优点包括标准的III—V族衬底材料和技术、良好的热稳定性、大面积、低研发成本以及抗辐射性。QWIP的另一个重要优点是具有带隙工程能力。可以通过调节量子阱宽度和势垒组分设计出满足特殊要求（例如多色焦平面列阵应用）的器件结构。介绍了对QwIP探测物理机制的理解以及近年来多色QwIP技术的发展状况。     

Swept away [quantum-well infrared photodetectors]

The ultra high-speed capability of quantum-well infrared photodetectors (QWIPs) is well known, thanks to their intrinsic short carrier lifetime (/spl sim/5 ps). This obviously makes QWIPs well suited for high-speed and high-frequency applications. In the past, for thermal infrared imaging where devices are optimized to have the highest possible detectivity, the absorption quantum efficiency has been low (<10%). For high-speed applications where lasers are usually used, the most important parameter is the absorption efficiency. We show that high absorption (/spl sim/100%) can be easily achieved by simply changing some of the device parameters. We also review the experimental demonstrations of the high-speed capability. At present, QWIPs hold the unique position of having high-speed/-frequency capability and high absorption for the thermal infrared region. There are no competitive alternatives.     

多色量子阱红外探测器的发展

军用红外探测器需要使用工作在各种红外波段的大规格、高均匀性多色焦平面阵列器件.满足这些要求的一个候选者就是量子阱红外（光电）探测器（Quantum Well Infrared Photodetector,QWIP）.作为新一代红外探测器,QWIP基于极薄半导体异质结构中的载流子束缚效应. GaAs/AlGaAs/QWIP的主要优点包括标准的Ⅲ-Ⅴ族衬底材料和技术、良好的热稳定性、大面积、低研发成本以及抗辐射性.QWIP的另一个重要优点是具有带隙工程能力.可以通过调节量子阱宽度和势垒组分设计出满足特殊要求（例如多色焦平面列阵应用）的器件结构.介绍了对QWIP探测物理机制的理解以及近年来多色QWIP技术的发展状况.     

中波-长波双色量子阱红外探测器

采用n型掺杂的AlGaAs/GaAs和AlGaAs/InGaA多量子阱材料,基于MOCVD外延生长技术,利用成熟的GaAs集成电路加工工艺,设计并制作了不同结构的中波-长波双色量子阱红外探测器(QWIP)器件,器件采用正面入射二维光栅耦合,光栅周期设计为4μm,宽度2μm;对制作的500μm×500μm大面积双色QWIP单元器件暗电流、响应光谱、探测率进行了测试和分析。在-3V偏压、77K温度和300K背景温度下长波(LWIR)和中波(MWIR)QWIP的暗电流密度分别为0.6、0.02mA/cm2;-3V偏压、80K温度下MWIR和LWIR QWIP的响应光谱峰值波长分别为5.2、7.8μm;在2V偏压、65K温度下,LWIR和MWIR QWIP的峰值探测率分别为1.4×1011、6×1010cm.Hz1/2/W。     

化合物半导体器件与电路的研究进展

介绍了GaAs,InP和GaN等几种重要化合物半导体电子器件的特点、应用和发展前景。回顾了GaAs,InP和GaN材料的材料特性及其器件发展历程与现状。分别讨论了GaAs基HEMT由PHEMT渐变为MHEMT结构和性能的变化,GaAs基HBT在不同电路应用中器件的特性,InP基HEMT与HBT的器件结构及工作特性,GaN基HEMT与HBT的器件特性参数。总体而言,化合物半导体器件与电路在高功率和高频电子器件方面发展较快,GaAs,InP和GaN材料所制得的各种器件电路工作在不同的频率波段,其在相关领域发展潜力巨大。     

Demonstration and Performance Assessment of Large Format InP–InGaAsP Quantum-Well Infrared Photodetector Focal Plane Array

There have been various studies showing that InP-InGaAs quantum-well infrared photodetectors (QWIPs) are potential alternatives to AlGaAs-GaAs QWIPs in the long wavelength infrared (LWIR) band, especially for applications requiring high responsivity. Being on InP substrate, this material system also offers lattice matched mid-wavelength infrared (MWIR)/LWIR dual band QWIP stack when it is used with the AlInAs-InGaAs system. It is desirable to extend the cut-off wavelength of InP based LWIR QWIPs to , which can be accomplished by replacing the QW material with InGaAsP. In this paper, we report the first InP-InGaAsP QWIP focal plane array (FPA). The 640 512 FPA displayed remarkably low noise equivalent temperature difference (NETD) with very short integration times (46 mK at 66 K with and f/1.5 optics). The results show that these QWIPs can be operated with high responsivity (1 A/W) while offering bias adjustable gain in a wide range where the detectivity is almost constant at a reasonably high level.     

分子束外延生长InGaAs/GaAs异质结及其在独特场效应晶体管中的应用

用分子束外延技术生长了ＩｎＧａＡｓ／ＧａＡｓ异质结材料,并用ＨＡＬＬ效应法和电化学Ｃ－Ｖ分布研究其特性。讨论了ＩｎＧａＡｓ／ＧａＡｓ宜质结杨效应晶体管（ＨＦＥＴ）的优越性。和ＧａＡｓ ＭＥＳＦＥＴＳ或ＨＥＭＴ相比,由于ＨＦＥＴ没有Ａｌ组份,具有低温特性好,低噪声和高增益等特点。本文研究了具有ＩｎＧａＡｓ／ＧａＡｓ双沟道和独特掺杂分布的低噪声高增益ＨＦＥＴ。     

Recent Progress in Mid- and Far-Infrared Semiconductor Detectors

The recent developments of semiconductor infrared detectors in extending the wavelength coverage and improving the focal plane array (FPA) performance are reviewed. The emphasis is on the GeSi/Si heterojunction infrared photoemission detectors (HIPs), GaAs/AlGaAs quantum well infrared photodetecots (QWIPs), Si, Ge and GaAs blocked impurity band detectors (BIBS), and Si and GaAs homojunction interfacial work-function internal photo-emission (HIWIP) far-infrared (FIR) detectors. The advantages, current status, and potential limitations of these infrared detectors have also been discussed.     

Gallium arsenide finds a new niche

The use of a very-large-scale integrated GaAs circuits for applications where high speed at room temperatures is needed, such as in computers or telecommunications, is examined. The advantages and disadvantages of a logic family called direct-coupled FET logic (DCFL) which couples the speed of GaAs with a significantly lower power dissipation than any other alternative are discussed. Material, fabrication, and packaging concerns associated with DCFL are considered. Some GaAs devices being produced in volume, at rates of several hundred a month, are described. The potential impact of these devices on the computer and telecommunications markets is addressed     

High linearity performances of GaN HEMT devices on silicon substrate at 4 GHz

In this letter, we demonstrate that, for high linearity application, GaN devices benefit from their high drain-source bias voltages. An improvement up to 20 dB in intermodulation ratio can be observed at high power levels compared to usual GaAs PHEMT devices. This study demonstrates that the high bandgap GaN devices are ideal candidates for the applications requiring high power and linearity simultaneously.     

新型电子器件和光学器件的共振隧穿结构

描述了一种新型共振隧穿结构器件，这种器件包含了通过可变间隙超晶格能量滤波器（ＶＳＳＥＦ）中的耦合量子附态的隧穿过程．论证了通过ＡｌＡｓ／ＧａＡｓＶＳＳＥＦ器件高能态和ＡｌＧａＡｓ／ＧａＡｓ超晶格受激态的共振隧穿，描述了这种器件作为较高功率微波源和共振隧穿晶体管的应用，并讨论了共振隧穿结构作为雪崩探测器和红外发射器等光学器件的潜在应用．     

Novel Type of Wide-Bandwidth GaAs/AIGaAs Infrared Photodetectors

A novel asymmetrical GaAs/AlGaAs photoconductance infrared detector based on the new idea proposed in this paper has been developed,which uses the intersubband transition within the same conduction (valence) band due to infrared radiation. The detectors with two wells or six wells grown by Metalorganic Chemical Vapor Deposition (MOCVD) system are fabricated by etching a mesa size of 200tμm ×200μm. Evident infrared absorption on the wavelength from 5 to 10μm has been observed for two samples,so has the peak of negative differential conductance. It is demonstrated that the photocurrent together with the signal-to-noise ratio increases with the number of the wells, but have nothing to do with the increase of the noise current under the same electric field,i, e.,the voltage drops per period,as is different from the conventional GaAs/AlGaAs Quantum Well Infrared Photodetectors (QWIPs). The noise current is one order's magnitude lower than that of the conventional GaAs/AlGaAs QWIPs. It is anticipated that the photocurrent and detector performances can be improved further by increasing the number of wells and optimizing the structural parameters.     

Opportunities in high performance ICs

The high performance of next generation ICs will, according to worldwide market analysts Henderson Ventures, help create new OEM markets. Among the devices helping to make those equipment markets worth $317bn by 1996 will be GaAs ICs. What are the prospects for this market, where are the applications? Most importantly, which companies are in the Top 10 league of manufacturing production for advanced ICs such as GaAs ICs?     

QUANTUM MECHANICAL MODEL AND SIMULATION OF GaAs／AlGaAs QUANTUM WELL INFRARED PHOTODETECTOR—Ⅱ ELECTRICAL ASPECTS

ＩｎｔｒｏｄｕｃｔｄｏｎＩｎｔｈｅｆｉｒｓｔｐａｒｔ ,ｗｅｈａｖｅｄｉｓｃｕｓｓｅｄｔｈｅｏｐｉｔｉｃａｌａｓｐｅｃｔｓａｂｏｕｔｔｈｅｑｕａｎｔｕｍｗｅｌｌｉｎｆｒａｒｅｄｐｈｏｔｏｄｅｔｅｃ ｔｏｒ .Ｈｅｒｅｗｅｃｏｎｔｉｎｕｅｄｉｓｃｕｓｓｉｏｎｓａｂｏｕｔｔｈｅｅｌｅｃｔｒｉｃａｌａｓｐｅｃｔｅｓｏｆｔｈｅｄｅｖｉｃｅｍｏｄｅｌａｎｄｓｉｍｕｌａｔｉｏｎ .1　ＤａｒｋＣｕｒｒｅｎｔａｎｄＰｈｏｔｏｃｕｒｒｅｎｔＤｉｓｔｒｉｂｕｔｅｄｅｆｆｅｃｔｓｏｆｅｘｔｅｒｎａｌｂｉａｓａｃｒｏｓｓｔｈ…     

An introduction to GaAs/GaAlAs HBTs for power applications

This paper presents a brief introduction to GaAs/GaAlAs heterojunction bipolar transistors (HBTs) for microwave and millimetre-wave power applications. The theoretical advantages of the heterojunction are outlined and the benefits of its incorporation in DC, RF and power devices are discussed. The problems inherent in the realization of HBTs in terms of device design, epitaxial material growth and device fabrication are discussed and the performance characteristics for practical devices presented. The paper concludes with a look at state-of-the-art GaAs/GaAlAs HBT performance and its standing with respect to the competing technologies of the metal semiconductor field effect transistor (MESFET) and the high electron mobility transistor (HEMT).     

A comparative analysis of GaAs and Si ion-implanted MESFET's

In this work, numerical calculations of device characteristics including theI-Vcharacteristic, small-signal parameters, and cutoff frequency are reported for silicon-implanted MESFET devices. The device dimensions and impurity profile are similar to those of GaAs MESFET's. Although Si MESFET devices have not found practical applications, these calculations provide a good comparison of the intrinsic frequency limits of GaAs and Si. Comparative analysis shows that there are differences in the magnitude of the small-signal parameters and channel current between GaAs and Si MESFET devices with the same geometries and implanted profiles. However, the general variations of small-signal parameters with respect to the drain voltage is similar for both materials. In addition, the calculations show that a 1-µm channel length GaAs MESFET device has a higher cut-off frequency by a factor of 1.8 than a similar Si MESFET. These results indicate that GaAs devices are intrinsically better suited for very high-speed switching devices.     

Study of degradation mechanisms in compound semiconductor based devices by SEM-cathodoluminescence

This papers reports on the microcharacterization of devices for optoelectronic and high-speed electronic applications by spectrally resolved cathodoluminescence. The advantages offered by the high lateral resolution, monochromatic imaging and depth resolved spectral analysis of the technique are presented. In particular, Inp based semiconducting optical amplifiers and GaAs based pump lasers for optical fiber communications are characterized from the point of view of compositional inhomogeneities and defect generation in the active regions. GaAs based heterojunction bipolar transistors and high electron mobility transitors are studied to respectively reveal Be outdiffusion from the base and break down walkout after bias aging. GaAs based solar cells are also investigated to show the correlation between dislocations and impurity gettering. Finally the limits of the technique are briefly discussed.     

High responsivity InP-InGaAs quantum-well infrared photodetectors: characteristics and focal plane array performance

We report the detailed characteristics of long-wavelength infrared InP-In/sub 0.53/Ga/sub 0.47/As quantum-well infrared photodetectors (QWIPs) and 640/spl times/512 focal plane array (FPA) grown by molecular beam epitaxy. For reliable assessment of the detector performance, characterization was performed on test detectors of the same size and structure with the FPA pixels. Al/sub 0.27/Ga/sub 0.73/As-GaAs QWIPs with similar spectral response (/spl lambda//sub p/=/spl sim/7.8 /spl mu/m) were also fabricated and characterized for comparison. InP-InGaAs QWIPs (20-period) yielded quantum efficiency-gain product as high as 0.46 under -3-V bias with a 77-K peak detectivity above 1/spl times/10/sup 10/ cm/spl middot/Hz/sup 1/2//W. At 70 K, the detector performance is background limited with f/2 aperture up to /spl sim/ 3-V bias where the peak responsivity (2.9 A/W) is an order of magnitude higher than that of the AlGaAs-GaAs QWIP. The results show that impact ionization in similar InP-InGaAs QWIPs does not start until the average electric-field reaches /spl sim/25 kV/cm, and the detectivity remains high under moderately large bias, which yields high responsivity due to large photoconductive gain. The InP-InGaAs QWIP FPA offers reasonably low noise equivalent temperature difference (NETD) even with very short integration times (/spl tau/).70 K NETD values of the FPA with f/1.5 optics are 36 and 64 mK under bias voltages of -0.5 V (/spl tau/=11 ms) and -2 V (/spl tau/=650 /spl mu/s), respectively. The results clearly show the potential of InP-InGaAs QWIPs for thermal imaging applications requiring high responsivity and short integration times.     

Technology, circuit design and applications of GaAs MMICs

Gallium arsenide monolithic microwave integrated circuits (GaAs MMICs) are a means of utilising the high-mobility, high-frequency aspects of the GaAs MESFET together with the semi-insulating properties of gallium arsenide to form a low-loss integrated circuit with active elements. Novel semiconductor growth structures allow devices with cut-off frequencies well into the millimetre wave ranges to be fabricated, with dramatic improvements in gain and noise figure. Multilevel structures also permit very high circuit densities, so complete receivers and phased-array radar multifunction circuits can be made with high repeatability in a few square millimetres. The authors discuss various aspects of the production process including process control and reliability. The materials used for GaAs MMICs and the fabrication technology used are discussed as are their applications. Future MMIC technology developments are also discussed