InAs 单量子点中级联辐射光子的关联测量

利用分子束外延生长InAs单量子点样品,温度为5 K时,测量了单量子点中单、双激子自发辐射的荧光(PL)光谱.研究了单、双激子发光强度随激发功率的变化及对应发光峰的偏振特性和精细结构劈裂.基于Hanbury-Brown Twiss(HBT) 实验,测量了单、双激子间发光光谱的关联函数,证实了其发光过程为级联发射过程. 关键词： InAs 单量子点 单、双激子 荧光光谱 级联辐射     

体心立方Ta的广义面错能及在Ⅱ型裂纹尖端初始塑性研究中的应用

基于嵌入原子势考察体心立方(bcc)金属Ta的广义层错能和广义孪晶能并获得广义层错能和广义孪晶能曲线. 研究表明,bcc Ta的广义层错能曲线与面心立方金属的广义层错能曲线有明显差异,Ta的广义层错能曲线不存在明显的能量极小值,位错主要以全位错的形式发射. 不同原子厚度的广义孪晶能曲线表明4个原子层的孪晶能曲线开始出现亚稳定的能量极小值,5个原子层的孪晶能曲线出现稳定的能量极小值. 为进一步验证广义层错能和广义孪晶能曲线揭示的塑性变形机理,采用准连续介质力学多尺度方法研究Ⅱ型裂纹尖端的初始塑性变形过程. 关键词： 广义层错能 广义孪晶能 体心立方金属钽 Ⅱ型裂纹     

金纳米颗粒调控量子点激子自发辐射速率

将InAs/GaAs量子点样品薄膜置于覆盖有直径为50 nm的金(Au)纳米颗粒的硅衬底上,可以调控量子点激子的自发辐射速率.实验发现,当量子点浸润层距离Au纳米颗粒表面15—35 nm时,激子自发辐射速率受到抑制,且距离为19 nm时抑制作用最大,导致量子点激子的自发辐射速率减小到没有Au纳米颗粒时自发辐射速率的10^-3.基于经典的偶极辐射模型模拟计算的激子自发辐射速率与实验结果一致.     

新型量子点场效应增强型单光子探测器

针对量子点场效应单光子探测器(QDFET)光吸收效率低下的问题, 提出了一种新型量子点场效应增强型单光子探测器(QDFEE-SPD). QDFEE-SPD增加了共振腔的设计, 并采用了GaAs/AlAs多层膜作为下反射镜; 对QDFEE-SPD的光吸收增强效应和光响应度进行了理论分析和模拟, 结果表明, 与没有共振腔时相比, QDFEE-SPD的吸收效率和光相应度都有了大幅度的提升, 同时为了光吸收的最优化, 吸收层厚度一般应在0.1–0.5 μm; 对QDFEE-SPD的材料样品进行了生长和测试实验, 反射谱测试和PL谱测试结果表明, QDFEE-SPD对入射光的吸收具有了明显的增强效应. 文章成果为高效率量子点场效应单光子探测技术的研究提供了新的思路. 关键词： QDFEE-SPD 共振腔 吸收效率 光吸收增强效应     

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.     

基于近地面高光谱影像的冬小麦日光诱导叶绿素荧光提取与分析

结合FluorMOD模型模拟数据与利用光谱分辨率3.3 nm、光谱采样间隔为0.71~0.74 nm近地面成像高光谱系统获取的抽穗期小麦高光谱影像比较3种基于夫琅和费线暗线的提取方法(FLD,3FLD和iFLD)的精确性和稳定性。结果表明当光谱分辨率为3.3 nm时,在760 nm附近的O₂-A波段可以有效提取日光诱导叶绿素荧光,而在687 nm附近的O₂-B波段不适合。当存在噪声时,FLD和3FLD的稳定性高于iFLD,FLD倾向于高估荧光值。     

基于MATLAB的《导航原理与系统》课程教学方法改革

《导航原理与系统》课程是非常具有民航特色的一门专业课程.由于陆基无线电导航系统设备价格比较昂贵,在教学中学生很难直接接触这些设备,因此本文把MATLAB语言应用到导航原理与系统课程的教学中,利用MATLAB软件实现陆基无线电导航系统的仿真,从而使学生可以进一步掌握陆基无线电导航设备的原理,为学生从事航空电子设备维修工作、技术管理工作和研究工作奠定坚实的基础.     

面向民航需求的通信工程专业建设综合改革

结合现代民航空管领域对通信工程专业人才需求的特点,设计了具有行业特色的专业综合改革建设方案,包括师资队伍建设、课程与教学资源建设、人才培养模式改革,教学方式与方法改革以及教学管理改革等方面,给出了主干课程体系图,为加强工程教育、突出专业特色,更好地为行业服务奠定了基础.     

Double-layer indium doped zinc oxide for silicon thin-film solar cell prepared by ultrasonic spray pyrolysis

Indium doped zinc oxide(ZnO:In) thin films were prepared by ultrasonic spray pyrolysis on corning eagle 2000 glass substrate.1 and 2 at.% indium doped single-layer ZnO:In thin films with different amounts of acetic acid added in the initial solution were fabricated.The 1 at.% indium doped single-layers have triangle grains.The 2 at.% indium doped single-layer with 0.18 acetic acid adding has the resistivity of 6.82×10-3Ω·cm and particle grains.The doublelayers structure is designed to fabricate the ZnO:In thin film with low resistivity(2.58×10-3Ω·cm) and good surface morphology.It is found that the surface morphology of the double-layer ZnO:In film strongly depends on the substratelayer,and the second-layer plays a large part in the resistivity of the double-layer ZnO:In thin film.Both total and direct transmittances of the double-layer ZnO:In film are above 80% in the visible light region.Single junction a-Si:H solar cell based on the double-layer ZnO:In as front electrode is also investigated.     

Spin Relaxation of Electrons in Single InAs Quantum Dots

By using polarization-resolved photoluminescence spectra, we study the electron spin relaxation in single InAs quantum dots （QDs） with the configuration of positively charged excitons X＋ （one electron, two holes）. The spin relaxation rate of the hot electrons increases with the increasing energy of exciting photons. For electrons localized in QDs the spin relaxation is induced by hyperfine interaction with the nuclei. A rapid decrease of polarization degree with increasing temperature suggests that the spin relaxation mechanisms are mainly changed from the hyperfine interaction with nuclei into an electron-hole exchange interaction.