VPE ZnSxSe1-x外延膜的生长及其光致发光

本文用气相外延(VPE)法在(100)GaAs衬底上生长了ZnSxSe1-x外延膜,并通过改变ZnS源温度和衬底温度使组分x值控制在0—1范围内。外延膜在77K时的光致发光(PL)光谱的近带边发射峰很强,半高宽较窄,这表明VPE ZnSxSe1-x外延膜的质量较高。     

基于LabVIEW的外延片光致发光扫描系统

概述了一套基于LabVIEW而搭建的半导体光致发光扫描系统.充分考虑扫描过程中由于外延片荧光信号过于微弱、不均匀背景光噪音可能产生的光谱采集失真以及随后分析谱图所存在的物理参量读取误差等因素,通过扣除背光源、隔离样品、高斯拟合等方式对测量过程进行优化.同时依托LabVIEW自身强大的仪器控制能力,如调用动态链接库与ActiveX控件实现了对光谱仪和平移台的通信与控制,结合其良好的数据分析及显示能力,实现了对外延片测量、读取、分析处理以及实时显示等过程的自动化整合,准确高效地提取出样品空间分辨的光致发光特性如峰位、光强等.最后初步分析了所用外延片的发光均匀性,得出波长分布与生长温度分布基本一致,肯定了保持生长腔内温度均匀一致的重要性.该系统不仅界面友好、简单易操作、实时性强、智能化高且搭建简单易行,极大地降低了成本,方便研究人员进行快捷准确的测试.     

基于LabVIEW的外延片光致发光扫描系统

概述了一套基于LabVIEW而搭建的半导体光致发光扫描系统.充分考虑扫描过程中由于外延片荧光信号过于微弱、不均匀背景光噪音可能产生的光谱采集失真以及随后分析谱图所存在的物理参量读取误差等因素,通过扣除背光源、隔离样品、高斯拟合等方式对测量过程进行优化.同时依托LabVIEW自身强大的仪器控制能力,如调用动态链接库与ActiveX控件实现了对光谱仪和平移台的通信与控制,结合其良好的数据分析及显示能力,实现了对外延片测量、读取、分析处理以及实时显示等过程的自动化整合,准确高效地提取出样品空间分辨的光致发光特性如峰位、光强等.最后初步分析了所用外延片的发光均匀性,得出波长分布与生长温度分布基本一致,肯定了保持生长腔内温度均匀一致的重要性.该系统不仅界面友好、简单易操作、实时性强、智能化高且搭建简单易行,极大地降低了成本,方便研究人员进行快捷准确的测试.     

应力和掺杂对Mg:GaN薄膜光致发光光谱影响的研究

对化学气相沉积(MOCVD)法在宝石衬底上生长的Mg掺杂GaN薄膜的表面及其GaN缓冲层的光致发光(PL)光谱进行了测量，用Raman光谱和x射线衍射(XRD)对GaN薄膜中的应力进行确定，通过PL光谱中的中性束缚激子跃迁能量的变化确定薄膜中应力的影响，从而研究Mg掺杂对p型GaN的DAP跃迁影响规律. 关键词： 光致发光 应力 Raman光谱     

分子束外延生长的(GaAs1－xSbx/InyGa1－yAs)/GaAs量子阱光致发光谱研究

报道了(GaAs_1-xSb_x/In_yGa_1-yAs)/Ga As量子阱结构的分子束外延生长与光致发光谱研究结果.变温与变激发功率光致发光谱的研究表明了此结构 为二型量子阱发光性质.讨论了光谱双峰结构的跃迁机制.通过优化生长条件，获得了室温1 31μm发光. 关键词： 分子束外延 量子阱 二型发光     

Si基GaN外延层光致发光光谱与二次离子质谱的研究

报道了在Si基上用简便的真空反应法制备出GaN外延层．光致发光光谱测试结果表明不同的生长温度和退火工艺会对GaN外延层的发光特性产生影响,在1050℃下生长的GaN外延层的发光强度高于其他温度下生长的发光强度,退火可以使GaN外延层的发光强度增强．二次离子质谱(SIMS)测试结果表明外延层中Ga和N分布均匀,在表面处Ga发生了偏聚,同时外延层中还存在Si,O等杂质,这使得外延层中背景电子浓度高达1.7×10¹⁸/cm³. SIMS测试结果还表明,在外延生长前采用 关键词：     

高质量氮化镓材料的光致发光研究

利用氨气源分子束外延（GSMBE）技术,在改型Ⅳ型分子束外延设备上生长高质量GaN单晶外延材料,并对样品进行了光致发光测量。分析室温和低温光致发光谱,系统地研究GaN的发光峰及其起源,并对常见的黄色发光带现象及其微结构起因进行探讨。     

界面形核时间对GaN薄膜晶体质量的影响

利用金属有机化学气相沉积技术系统研究了界面形核时间对c面蓝宝石衬底上外延生长GaN薄膜晶体质量的影响机理. 用原子力显微镜、扫描电子显微镜、高分辨X射线衍射仪以及光致发光光谱仪表征材料的晶体质量以及光学性质. 随着形核时间的延长, 退火后形成的形核岛密度减小、尺寸增大、均匀性变差, 使得形核岛合并过程中产生的界面数量先减小后增大, 导致GaN外延层的螺位错和刃位错密度先减小后增大, 这与室温光致发光光谱中得到的带边发光峰与黄带发光峰的比值先增大后降低一致. 研究结果表明, 外延生长过程中, 界面形核时间会对GaN薄膜中的位错演变施加巨大影响, 从而导致GaN外延层的晶体质量以及光学性质的差异.     

截止波长12 μm的p型-InAs0.04Sb0.96材料的熔体外延生长

为了获得p-型的长波长InAsSb材料并研究掺杂剂Ge对材料特性的影响,用熔体外延法生长了掺Ge的波长为12 μm的p型-InAsSb 外延层.用傅里叶红外光谱仪、Van der Pauw 法和电子探针微分析研究了材料的透射光谱、电学性质以及组分的分布.结果表明,两性杂质Ge在熔体外延生长的InAs0.04Sb0.96材料中起受主杂质作用.当外延层的组分相同时,材料的截止波长不随掺Ge浓度的变化而变化,但是随着外延层中掺Ge量的增加,外延层的透射率下降.掺杂原子Ge在外延层的表面及生长方向的分布都是相当均匀的.77 K下测得,载流子浓度为9.18×1016 cm－3的掺Ge的p型-InAs0.04Sb0.96样品,其空穴迁移率达到1 120 cm2·Vs－1.     

N型4H-SiC同质外延生长

利用水平式低压热壁CVD (LP-HW-CVD) 生长系统,台阶控制生长和衬底旋转等优化技术,在偏晶向的4H-SiC Si(0001) 晶面衬底上进行4H-SiC同质外延生长,生长温度和压力分别为1550℃和10⁴ Pa,用高纯N₂作为n型掺杂剂的4H-SiC原位掺杂技术,生长速率控制在5μm/h左右.采用扫描电镜(SEM)、原子力显微镜(AFM),傅里叶变换红外光谱(FTIR)和Hg/4H-SiC肖特基结构对同质外延表面形貌、厚度、掺杂浓度以及均匀性进行了测试.实验结果表明,4H-SiC同质外延在表面无明显缺陷,厚度均匀性1.74%, 1.99% 和1.32%(σ/mean),掺杂浓度均匀性为3.37%,2.39%和2.01%.同种工艺条件下,样品间的厚度和掺杂浓度误差为1.54%和3.63%,有很好的工艺可靠性. 关键词： 4H-SiC 同质外延生长 水平热壁CVD 均匀性     

MICROSTRUCTURE AND LUMINESCENCE PROPERTIES OF GaxIn1-xP/GaAs HETEROSTRUCTURE

The Ga_xIn_1-xP/GaAs heterostructures with different x values have been investigated by photoluminescence (PL), energy dispersive spectrum (EDS), and transmission electron microscopy (TEM). Experimental results suggested that the composition of epitaxial layers evidently affected the microstructure of the heterostructures. When x value was close to 0.5, the defects in the epitaxial layer decreased, and the lattice match between film and sub-strate approached optimum, Meanwhile, the heteroatructure provided a high luminescence efficiency.     

MICROSTRUCTURE AND LUMINESCENCE PROPERTIES OF GaxIn1-xP/GaAs HETEROSTRUCTURE

The Ga_xIn_1-xP/GaAs heterostructures with different x values have been investigated by photoluminescence (PL), energy dispersive spectrum (EDS), and transmission electron microscopy (TEM). Experimental results suggested that the composition of epitaxial layers evidently affected the microstructure of the heterostructures. When x value was close to 0.5, the defects in the epitaxial layer decreased, and the lattice match between film and sub-strate approached optimum, Meanwhile, the heteroatructure provided a high luminescence efficiency.     

Optical measurements of stress distributions in GaAs at low temperature

We have measured the stress distribution at He temperature on two epitaxial GaAs wafers which were compressed along one edge. The stress was determined non-destructively at different points on the wafer surface by using the line-splitting and the lineshifts of the photoluminescence spectra of the acceptor-bound excitons in comparison with calibration spectra at known uniaxial stress.     

硅基低位错密度厚锗外延层的UHV/CVD法生长

利用超高真空化学气相淀积系统, 基于低温缓冲层和插入应变超晶格的方法, 在Si(100)衬底上外延出厚度约为880 nm的纯Ge层. 采用X射线双晶衍射、高分辨透射电镜、原子力显微镜和光致发光谱分别表征了其结构及光学性质. 测试结果显示外延Ge的X射线双晶衍射曲线半高宽为273", 表面均方根粗糙度为0.24 nm, 位错密度约为1.5×10⁶ cm². 在室温下观测到外延Ge的直接带跃迁光致发光, 发光峰值位于1540 nm. 表明生长的Si基Ge材料具有良好的结晶质量, 可望在Si基光电子器件中得到应用.     

多孔硅镍钝化处理的光致发光谱研究

报道了对多孔硅在NiCl2中电解钝化处理的一种新方法,观测了经不同时间处理后多孔硅的光致发光谱,其光谱表明,恰当的处理条件,可使峰值强度增大约2．5倍,峰值波长蓝移33nm,分析了现象发生的原因是由于多孔硅表面的SiHx中的H被Ni替换成SiNix的结果。     

Comprehensive uniformity analysis of GaAs-based VCSEL epiwafer by utilizing the on-wafer test capability

A comprehensive study of the uniformity of 850 nm VCSEL epiwafer grown by the MOCVD technique is presented. By utilizing the VCSEL planar structure, uniformity test is performed on-wafer directly, besides using the conventional photoluminescence technique. The VCSEL quantum wells are found to exhibit a peak emission wavelength of 839.5 nm. Also, the grown epiwafer is observed to exhibit a Fabry–Perot cavity resonance at 846.5 nm. Various VCSEL devices fabricated from the center to the edge of the VCSEL epiwafer show a similar trend towards the light–current and output spectral characteristics. However, the device existing near the epiwafer edge is observed to exhibit significantly different characteristics, which is attributed to the physical conditions of the device near the edge, and also the limitations of the epitaxial growth.     

Effect of composition fluctuations on radiative recombination in narrow-gap semiconductor solid solutions

The photoluminescence of the epitaxial structures based on the narrow-gap CdHgTe solid solutions has been experimentally investigated and the presence of large-scale composition fluctuations localizing carriers in the structures has been established. A model has been proposed for describing the effect of the fluctuations on the radiative recombination rate, the shape of the luminescence spectra, and their peak position. The model describes carrier transport and recombination at the strongly inhomogeneous composition of the solid solution and demonstrates the manifestation of carrier localization in the luminescence spectra.     

Comparison of compensation ratios determined by photoluminescence and electrical methods in epitaxial GaAs

Compensation ratios in high purity epitaxial GaAs layers are determined by Nam et al.'s photoluminescence method at a well-defined finite excitation intensity. This excitation intensity is obtained from the excitation-dependence of the peak energy of the neutral donor-acceptor transition. The values of compensation ratio determined in this way are in excellent agreement with those obtained by the conventional electrical method.