Characterization of GaNxAs1-x Alloy Grown on GaAs by Molecular Beam Epitaxy

Ga Nx As1 - x,the combination of small amount of nitrogen and Ga As,has beenexperimentally observed with the band gaps several hundreds me V lower than that ofGa As[1～ 4] .The alloy has attracted considerable attention in the applicat...     

MBE生长轻掺硅GaAs材料光荧光谱杂质特性研究

采用低温光荧光谱测试方法，研究了ＭＢＥ生长的轻掺硅ＧａＡｓ材料的杂质特性，并结合Ｈａｌｌ测量结果，讨论了ＭＢＥ关键生长条件Ⅴ／Ⅲ束流比等对Ｓｉ在ＧａＡｓ中掺杂特性的影响，研究表明掺杂元素Ｓｉ在ＧａＡｓ中起两性（施主或受主）杂质作用，适当提高Ⅴ／Ⅲ束流比可以抑制Ｓｉ的自补偿效应，从而减小载流子的补偿度，进一步提高迁移率。通过优化生长条件，本实验已获得了杂质浓度小于１０１２ｃｍ－３，７７Ｋ下迁移率大于１．６×１０５ｃｍ２／Ｖ·ｓ的高纯、高迁移率ＧａＡｓ材料。     

分子束外延ZnSe/ZnSxSe1-x超晶格光学特性

用分子束外延方法在GaAs(100)衬底上生长了高质量的ZnSe/ZnSxSe1-x(x=0.12)超晶格结构，通过X射线衍射谱和光致发光谱，对其结构特性和光学特性进行了研究。结果表明：在4．4K温度下，超晶格样品显示较强的蓝光发射，主发光峰对应于阱层ZnSe的基态电子到重空穴基态的自由激子跃迁，而且其峰位相对于ZnSe薄膜的自由激子峰有明显蓝移。从理论上分析计算了由变就和量子限制效应引起的自由激妇峰位移动，理论和实验结果相吻合。     

Effects of Growth Conditions on Optical Properties of GaInNAs/GaAs Quantum Well Grown by Molecular Beam Epitaxy

During the process of molecular beam epitaxy employing a DC plasma as N source,the effects of the growth temperature, growth rate and As4 pressure on the optical properties of GaInNAs Quantum Well(QW) are similar to those of InGaAs QW with the same In contents.In the range of 400 to 470℃, elevating growth temperature is beneficial to the improvement in the photoluminescence (PL) peak intensity of GaInNAs QW, but obviously broadens the fullwidth at half maximum PL peak. The improvement of optical properties and the reduction of N incorporation have been observed by increasing the growth rate. As4 pressure mainly affects the optical properties of GaInNAs QW rather than N incorporation does.     

High Resistivity Step-Graded InAIAs/GaAs Metamorphic Buffer Layers Grown by Molecular Beam Epitaxy in Low Temperature

High resistivity step-graded InAlAs/GaAs metamorphic buffer has been achieved on(001)SI.GaAs substrate by MBE in low temperature.The resistivity is 2.6×10^4Ω·cm in room temperature,when the growth temperature is 340℃.Surface morphology is observed by atomic force microscopy with RMS of 1.79nm.Furthermore,the ω-2θ scan using triple-axis X·ray diffraction shows that the sample has better crystalline quality.The electron transport properties of the buffer layers were investigated through variable temperature Hall measurements for the first time.The high resistivity mechanism was investigated by thermally stimulated current (TSC). The carrier concentrations and Hall mobilities of the InAlAs/InGaAs/GaAs MM-HEMT structure on low temperature step graded InAIAs metamorphic buffer layers grown in optimized conditions are high quality.     

分子束外延ZnSe/ZnS_xSe_(1-x)超晶格光学特性

用分子束外延方法在 Ga As(10 0 )衬底上生长了高质量的 Zn Se/ Zn Sx Se1 - x(x=0 .12 )超晶格结构 ,通过 X射线衍射谱和光致发光谱 ,对其结构特性和光学特性进行了研究 .结果表明 :在 4 .4 K温度下 ,超晶格样品显示较强的蓝光发射 ,主发光峰对应于阱层 Zn Se的基态电子到重空穴基态的自由激子跃迁 ,而且其峰位相对于 Zn Se薄膜的自由激子峰有明显蓝移 .从理论上分析计算了由应变和量子限制效应引起的自由激子峰位移动 ,理论和实验结果相吻合     

分子束外延硅基碲镉汞材料技术研究现状

目前,高性能大面阵中波及短波红外探测器已经得到了越来越多的应用。材料参数控制精确、材料质量良好的碲镉汞材料是获得高质量碲镉汞探测器的先决条件。报道了华北光电技术研究所在分子束外延(Molecular Beam Epitaxy, MBE)生长硅基中波及短波碲镉汞材料方面的最新研究进展,并介绍了现阶段MBE生长碲镉汞材料的研究现状。     

GSMBE外延生长SGOI材料的退火行为

在SIMOX SOI超薄硅衬底上外延生长了高质量SiGe合金薄膜来制备SGOI(SiGe on insulator)样品，并研究了其在1050℃氧化气氛中的高温退火行为．用Raman，DCXRD，RBS和光学显微镜等分析手段对SGOI样品在退火前后的性能进行了表征．分析结果表明：SGOI样品表面的穿透位错密度约为5e５ｃｍ－２；高温退火处理可以促进SGOI样品中异质外延生长SiGe合金薄膜的弛豫化和超薄Si夹层向SiGe合金薄膜的转化，进一步提高SiGe薄膜的晶体质量，并且有助于获得高Ge组分的SGOI材料．     

嵌入在Si衬底上的分子束外延GaAs层的微区喇曼和光致发光分析

对分子束外延生长的嵌入在Si衬底上的边长为20—150μm正方形GaAs层微区进行了微区喇曼和光致发光分析。发现微区GaAs层的喇曼散射谱和光致发光谱与普通平面Si片上生长的GaAs层的基本相同,证实嵌入式生长可以得到与通常平面生长基本相同的质量。仔细的分析表明随着微区尺寸的减小GaAs层的无序程度有少许增长。     

半导体/超晶格分布布拉格反射镜(DBR)的分子束外延生长

用分子束外延技术 (MBE)生长了以 Ga As/Al As超晶格替代 Alx Ga1 - x As所形成的 P型半导体 /超晶格分布布拉格反射镜 (DBR) .此分布布拉格反射镜的反射谱中心波长为 85 0 nm.由实验表明 ,19个周期的反射镜获得了高达 99%以上的高反射率 .与此同时 ,采取自行设计的二次钨丝掩膜质子注入法制成 15 μm× 15 μm的正方形电流注入区 ,以此测定 P型反射镜的串联电阻 ,克服了湿化学腐蚀法中腐蚀深度不易控制及侧面同时被腐蚀的缺点 ,实验得出此 P型反射镜的串联电阻仅为 5 0 Ω 左右 .在生长过程中 ,发现在只含一个铝源的分子束外延生长系统中 ,生长这种半     

分子束外延生长高应变单量子阱激光器

采用分子束外延方法研究了高应变 In Ga As/Ga As量子阱的生长技术 .将 In Ga As/Ga As量子阱的室温光致发光波长拓展至 116 0 nm,其光致发光峰半峰宽只有 2 2 me V.研制出 112 0 nm室温连续工作的 In Ga As/Ga As单量子阱激光器 .对于 10 0 μm条宽和 80 0 μm腔长的激光器 ,最大线性输出功率达到 2 0 0 m W,斜率效率达到 0 .84m W/m A,最低阈值电流密度为 45 0 A/cm2 ,特征温度达到 90 K.     

分子束外延生长高应变单量子阱激光器

采用分子束外延方法研究了高应变InGaAs/GaAs量子阱的生长技术.将InGaAs/GaAs量子阱的室温光致发光波长拓展至1160nm,其光致发光峰半峰宽只有22meV.研制出1120nm室温连续工作的InGaAs/GaAs单量子阱激光器.对于100μm条宽和800μm腔长的激光器,最大线性输出功率达到200mW,斜率效率达到0.84mW/mA,最低阈值电流密度为450A/cm2,特征温度达到90K.     

离子损伤对等离子体辅助分子束外延生长的 Ga NAs/ Ga As和Ga In NAs/ Ga As量子阱的影响

研究了离子损伤对等离子体辅助分子束外延生长的 Ga NAs/ Ga As和 Ga In NAs/ Ga As量子阱的影响 .研究表明离子损伤是影响 Ga NAs和 Ga In NAs量子阱质量的关键因素 .去离子磁场能有效地去除了等离子体活化产生的氮离子 .对于使用去离子磁场生长的 Ga NAs和 Ga In NAs量子阱样品 ,X射线衍射测量和 PL 谱测量都表明样品的质量被显著地提高 .Ga In As量子阱的 PL 强度已经提高到可以和同样条件下生长的 Ga In As量子阱相比较 .研究也表明使用的磁场强度越强 ,样品的光学质量提高越明显     

分子束外延生长Al_xGa_(1-x)As/GaAs超晶格及结构、光学特性研究

报道了分子束外延生长80个周期的Al_xGa_(1-x)As/GaAs超晶格,X射线衍射和透射电镜的结果表明超晶格样品有良好的结构特性,光反射光谱观察到阱内的电子跃迁过程,其结果与理论计算相符。     

Photoluminescence Characterization of Boron-doped Si Layers Grown by Molecular Beam Epitaxy

Photoluminescence spectra were used to characterize the boron-doped Si layers grown by molecular beam epitaxy using HBO2 as the doping source. The influence of boron doping concentration on the dislocation-related photoluminescence spectra of molecular beam epitaxy Si layers annealed at 900 ℃ was studied with different doping concentrations and growth temperature. The broad photoluminescence band（from 0.75 eV to 0. 90 eV） including D1 and D2 bands was associated with high boron doping concentration in the samples, while D3 and D4 bands might be related to oxygen precipitates.     

Characterization of HgCdTe Films Grown on Large-Area CdZnTe Substrates by Molecular Beam Epitaxy

Recent advances in growth of Hg_1?x Cd _x Te films on large-area (7 cm × 7.5 cm) CdZnTe (CZT) substrates is presented. Growth of Hg_1?x Cd _x Te with good uniformity on large-area wafers is achieved using a Riber 412 molecular beam epitaxy (MBE) tool designed for growth of Hg_1?x Cd _x Te compounds. The reactor is equipped with conventional CdTe, Te, and Hg sources for achieving uniform exposure of the wafer during growth. The composition of the Hg_1?x Cd _x Te compound is controlled in situ by employing a closed-loop spectral ellipsometry technique to achieve a cutoff wavelength (λ _co) of 14 μm at 78 K. We present data on the thickness and composition uniformity of films grown for large-format focal-plane array applications. The composition and thickness nonuniformity are determined to be <1% over the area of a 7 cm × 7.5 cm wafer. The films are further characterized by Fourier-transform infrared spectroscopy, optical microscopy, and Hall measurements. Additionally, defect maps show the spatial distribution of defects generated during the epitaxial growth of the Hg_1?x Cd _x Te films. Microdefect densities are in the low 10³ cm^?2 range, and void defects are below 500 cm^?2. Dislocation densities less than 5 × 10⁵ cm^?2 are routinely achieved for Hg_1?x Cd _x Te films grown on CZT substrates. HgCdTe 4k × 4k focal-plane arrays with 15 μm pitch for astronomical wide-area infrared imagers have been produced using the recently developed MBE growth process at Teledyne Imaging Sensors.     

Fabrication and Characterization of Small Unit-Cell Molecular Beam Epitaxy Grown HgCdTe-on-Si Mid-Wavelength Infrared Detectors

Small 15 μm unit-cell mid-wavelength infrared (MWIR) detectors have been fabricated and characterized at Raytheon Vision Systems (RVS) to enable the development of high resolution, large format, infrared imaging systems. The detectors are fabricated using molecular beam epitaxy (MBE) grown 4-in. HgCdTe-on-Si wafers with a p-on-n double layer heterojunction (DLHJ) device architecture. Advanced fabrication processes, such as inductively coupled plasma (ICP) etching, developed for large format MBE-on-Si wafers and 20 μm unit-cell two-color triple layer heterojunction (TLHJ) focal plane arrays (FPAs) have been successfully extended and applied to yield high performance 15 μm unit-cell single color detectors that compare favorably with state-of-the-art detectors with larger pitch. The measured 78 K MWIR cut-off wavelength for the fabricated detectors is near 5.5 μm, and the current–voltage characteristics of these devices exhibit strong reverse breakdown and RoA performance as a function of temperature with diffusion limited performance extending to temperatures down to 120 K.     

Microstructure of Heteroepitaxial ZnTe Grown on GaAs(211)B by Molecular Beam Epitaxy

ZnTe was grown on GaAs(211)B by molecular beam epitaxy (MBE). Structural properties and strain relaxation at the ZnTe/GaAs(211)B interface were investigated by high resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy (STEM). Application of digital image processing involving a filtered inverse fast Fourier transformation revealed an array of misfit dislocations at the interface and allowed strain relaxation to be estimated. Only one twin defect was observed in the HRTEM images, and details of this twin defect were investigated by STEM.     

分子束外延GaAs/Si应变层的光致发光和光反射谱研究

研究了分子束外延GaAs/Si光致发光谱的激发强度和温度依赖关系。确定出2个本征发光峰,分别对应于导带至m_J=±3/2和m_J=±1/2价带的复合。这种价带的移动和分裂归因于由GaAs和Si的热膨胀系数不同所引起的GaAs层双轴张应力。还观测到4个非本征发光峰,分别为导带至m_J=±1/2碳受主态发光、可能与缺陷有关的发光以及可能由Mn和Cu受主杂质引起的发光。室温下将GaAs/Si和GaAs/GaAs材料的光反射谱进行比较,前者明显向低能移动约8meV,观测到3个特征谱结构,与光致发光结果相一致。