GaAs Based InAs/GaSb Superlattice Short Wavelength Infrared Detectors Grown by Molecular Beam Epitaxy

InAs/GaSb superlattice （SL） short wavelength infrared photoconduction detectors are grown by molecular beam epitaxy on GaAs（O01） semi-insulating substrates. An interfacal misfit mode AISb quantum dot layer and a thick GaSb layer are grown as buffer layers. The detectors containing a 200-period 2 ML/S ML InAs/GaSb SL active layer are fabricated with a pixel area of 800×800 μm^2 without using passivation or antirefleetion coatings. Corresponding to the 50% cutoff wavelengths of 2.05μm at 77K and 2.25 μm at 300 K, the peak detectivities of the detectors are 4 × 10^9 cm·Hz^1/2/W at 77K and 2 × 10^8 cm·Hz1/2/W at 300K, respectively.     

基于JavaCard的云数据确定性删除方法

确定性删除将外包数据的删除问题转换为密钥的安全管控和删除问题,使得留存于云服务提供商和数据使用者处的外包数据是失效、不可恢复的。但是,现有的确定性删除方案大多是在资源充裕的计算机和智能手机上设计和实现的,无法应用于资源受限的嵌入式设备。本文提出了适用于JavaCard平台的云数据确定性删除方法。在该方法中,密钥的使用条件可以是时间,也可以是次数,数据属主可以根据其需要选取一种条件以实现密钥在数据使用者端的受限使用。对于这两种使用条件,数据使用者都可以将密钥及使用条件安全保存在本地,节省通信开销。当密钥使用条件满足时,JavaCard用密钥解密数据;当密钥使用条件不满足时,JavaCard安全删除密钥,并生成可公开验证的密钥删除证据。实验和对比分析表明,本文方案性能开销合理,能够实现预期目的,可以应用于嵌入式设备。     

High quality above 3-μm mid-infrared InGaAsSb/AlGaInAsSb multiple-quantum well grown by molecular beam epitaxy

The GaSb-based laser shows its superiority in the 3–4 μm wavelength range. However, for a quantum well(QW) laser structure of InGaAsSb/AlGaInAsSb multiple-quantum well(MQW) grown on GaSb, uniform content and high compressive strain in InGaAsSb/AlGaInAsSb are not easy to control. In this paper, the influences of the growth temperature and compressive strain on the photoluminescence(PL) property of a 3.0-μm InGaAsSb/AlGaInAsSb MQW sample are analyzed to optimize the growth parameters. Comparisons among the PL spectra of the samples indicate that the In0.485GaAs0.184Sb/Al0.3Ga0.45In0.25As0.22Sb0.78MQW with 1.72% compressive strain grown at 460 C posseses the optimum optical property. Moreover, the wavelength range of the MQW structure is extended to 3.83 μm by optimizing the parameters.     

High quality above 3-μm mid-infrared InGaAsSb/AIGaInAsSb multiple-quantum well grown by molecular beam epitaxy

The GaSb-based laser shows its superiority in the 3-4 ~tm wavelength range. However, for a quantum well （QW） laser structure of InGaAsSb/AIGaInAsSb multiple-quantum well （MQW） grown on GaSb, uniform content and high com- pressive strain in InGaAsSb/A1GaInAsSb are not easy to control. In this paper, the influences of the growth tempera- ture and compressive strain on the photoluminescence （PL） property of a 3.0μm lnGaAsSb/A1GaInAsSb MQW sample are analyzed to optimize the growth parameters. Comparisons among the PL spectra of the samples indicate that the Ino.485GaAso.184Sb/Alo.3Gao.45Ino.25Aso.22Sbo.78 MQW with 1.72% compressive strain grown at 460 ~C posseses the op- timum optical property. Moreover, the wavelength range of the MQW structure is extended to 3.83 μm by optimizing the parameters.     

Growth and Characterization of GaSb-Based Type-Ⅱ InAs/GaSb Superlattice Photodiodes for Mid-Infrared Detection

InAs/GaSb superlattiee （SL） midwave infrared photovoltaic detectors are grown by molecular beam epitaxy on GaSb（001） residud p-type substrates. A thick GaSb layer is grown under the optimized growth condition as a buffer layer. The detectors containing a 320-period 8ML/SML InAs/GaS5 SL active layer are fabricated with a series pixel area using anode sulfide passivation. Corresponding to 50% cutoff wavelengths of 5.0 μm at 77K, the peak directivity of the detectors is 1.6 × 10^10 cm.Hz^1/2 W^-1 at 77K.     

双层堆垛长波长InAs/GaAs量子点发光性质研究

研究了双层堆垛InAs/GaAs/InAs自组织量子点的生长和光致发光(PL)的物理性质。通过优化InAs淀积量、中间GaAs层厚度以及InAs量子点生长温度等生长条件,获得了室温光致发光1391～1438nm的高质量InAs量子点。研究发现对量子点GaAs间隔层实施原位退火、采用Sb辅助生长InGaAs盖层等方法可以增强高密度(2×1010 cm-2)InAs量子点的发光强度,减小光谱线宽,改善均匀性和红移发光波长。     

Room-Temperature Operation of 2.4 μm InGaAsSb/A1GaAsSb Quantum-Well Laser Diodes with Low-Threshold Current Density

GaSb-based 2.4μm InGaAsSb/AIGaAsSb type-I quantum-well laser diode is fabricated. The laser is designed consisting of three In0.35 Ga0.65As0.1Sb0.9/Al0.35 Ga0.65 As0.02Sb0.98 quantum wells with 1% compressive strain located in the central part of an undoped Al0.35Ga0.65As0.02Sb0.98 waveguide layer. The output power of the laser with a 50-μm-wide i-ram-long cavity is 28roW, and the threshold current density is 400A/cm2 under continuous wave operation mode at room temperature.     

Molecular Beam Epitaxy of GaSb on GaAs Substrates with AlSb Buffer Layers

We investigate the molecular beam epitaxy growth of GaSb films on GaAs substrates using AlSb buffer layers. Optimization of AlSb growth parameter is aimed at obtaining high GaSh crystal quality and smooth GaSh surface. The optimized growth temperature and thickness of AlSb layers are found to be 450℃ and 2.1 nm, respectively. A rms surface roughness of 0.67 nm over 10 × 10 μm^2 is achieved as a 0.5 μm GaSh film is grown under optimized conditions.     

Evolution of surface morphology and photoluminescence characteristics of 1.3-μm In_(0.5)Ga_(0.5)As/GaAs quantum dots grown by molecular beam epitaxy

Evolution of surface morphology and optical characteristics of 1.3-μm In0.5Ga0.5As/GaAs quantum dots （QDs） grown by molecular beam epitaxy （MBE） are investigated by atomic force microscopy （AFM） and photoluminescence （PL）. After deposition of 16 monolayers （ML） of In0.5Ga0.5As, QDs are formed and elongated along the [120] direction when using sub-ML depositions, while large size InGaAs QDs with better uniformity are formed when using ML or super-ML depositions. It is also found that the larger size QDs show enhanced PL efficiency without optical nonlinearity, which is in contrast to the elongated QDs.     

原子氢辅助分子束外延GaAs(331)A表面形貌演化

研究了GaAs高指数面(331)A在原子氢辅助下分子束外延形貌的演化.原子力显微镜测试表明：在常规分子束外延情况下,GaAs外延层台阶的厚度和台面的宽度随衬底温度的升高而增加,增加外延层厚度会导致台阶的密度和台面的宽度增加然后饱和.而在原子氢辅助分子束外延情况下,当GaAs淀积量相同时GaAs外延层台阶的密度增大宽度减小.认为这是由于原子氢的作用导致Ga原子迁移长度的减小.在GaAs(331)A台阶基底上生长出InAs自组织纳米线,用光荧光测试研究了其光学各项异性特征.