Growth and properties of GaN on Si (111) substrates with AlGaN/AlN buffer layer by NH3-GSMBE

We describe the growth of GaN on Si (111) substrates with a AlGaN/AlN buffer layer by NH3-GSMBE. The influence of the AlN and AlGaN buffer layer thickness on the crack density of GaN has been investigated. It is found that the optimum thickness is 120 nm and 250 nm for AlN and AlGaN layers, respectively. The full width at half maximum of the GaN (0002) peak in the triple-crystal x-ray rocking curve measurement is about 15 arcmin.

Structural properties and Raman measurement of AlN films grown on Si (111) by NH3-GSMBE

Epitaxial growth of AlN has been performed by molecular beam epitaxy (MBE) with ammonia. The structural properties of materials were studied by cross-sectional transmission electron microscopy (TEM), X-ray diffraction (XRD), and atomic force microscopy (AFM). XRD and TEM diffraction pattern confirm the AlN is single crystalline 2H-polytype with the epitaxial relationship of (0001)AlNparallel to(111)Si, [11 (2) over bar0](AlN)parallel to[110](Si), [10 (1) over bar0](AlN)parallel to[11 (2) over bar](Si). Micro-Raman scattering measurement shows that the E-2 (high) and A(1) (LO) phonon mode shift 9 cm(-1) toward the low frequency, which shows the existence of large tensile strain in the AlN films. Furthermore, the appearance of forbidden A, (TO) mode and its anomalous shift toward high frequency was found and explained. (C) 2002 Elsevier Science B.V. All rights reserved.

High phosphorous doping and morphological evolution during Si growth by gas source molecular beam epitaxy (GSMBE)

Uniform and high phosphorous doping has been demonstrated during Si growth by GSMBE using disilane and phosphine. The p-n diodes, which consist of a n-Si layer and a p-SiGe layer grown on Si substrate, show a normal I-V characteristic. A roughening transition during P-doped Si growth is found. Ex situ SEM results show that thinner film is specular. When the film becomes thicker, there are small pits of different sizes randomly distributed on the flat surface. The average pit size increases, the pit density decreases, and the size distribution is narrower for even thicker film. No extended defects are found at the substrate interface or in the epilayer. Possible causes for the morphological evolution are discussed. (C) 1999 Elsevier Science B.V. All rights reserved.

GSMBE growth and characterization of InxGa1-xAs/InP strained-layer MQWs in a P-i-N configuration

InxGa1-xAs/InP (0.39 less than or equal to x less than or equal to 0.68) strained-layer quantum wells having 20 wells with thickness of 50 Angstrom in a P-i-N configuration were grown by gas source molecular beam epitaxy (GSMBE). High-resolution X-ray diffraction rocking curves show the presence of up to seven orders of sharp and intense satellite reflection, indicative of the structural perfection of the samples. Low-temperature photoluminescence and low-temperature absorption spectra were used to determine the exciton transition energies as a function of strain. Good agreement is achieved between exciton transition energies obtained experimentally at low temperature with those calculated using the deformation potential theory.

Study of GSMBE growth and characteristics of high-quality strained In0.63Ga0.37As/InP quantum wells

High-quality compressively strained In0.63Ga0.37As/InP quantum wells with different well widths (1-11 nm) have been grown coherently on InP substrates using a home-made gas source molecular beam epitaxy (GSMBE) system. The indium composition in the wells of the sample was determined by means of high-resolution X-ray diffraction and its computer simulation. it is found that the exciton transition energies determined by photoluminescence (PL) at 10 K are in good agreement with those calculated using a deformation potential model. Sharp and intense peaks for each well can be well resolved in the 10 K PL spectra. For wells narrower than 4 nm, the line width of the PL peaks are smaller than the theoretical values of the line-width broadening due to 1 hit interface fluctuation, showing that the interface fluctuation of our sample is within 1 ML. For wells of 7 and 9 nm, the PL peak widths are as low as 4.5 meV.

GSMBE growth and PL investigation of lattice-matched InGaAs/InP quantum wells

Using a home-made gas-source molecular beam epitaxy system, high quality InGaAs quantum wells with different well widths lattice-matched to a (001) InP substrate have been obtained. Sharp and intense peaks for each well can be well resolved in the PL spectra for the sample. For well widths larger than similar to 60 Angstrom, the exciton energies are in good agreement with those of calculation. For wells narrower than 40 Angstrom, our line widths are below the theoretical values of line width broadening due to one monolayer interface fluctuation, showing that the interface fluctuation of our sample is within one monolayer.

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

GSMBE生长SiGe/Si材料的原位掺杂控制技术

在特定温控下对掺杂气体分子的状态和活性进行控制，建立了一套具有自主知识产权的气源分子束外延工艺生长SiGe/Si材料的原位掺杂控制技术。采用该技术生长的SiGe/Si HBT外延材料，可将硼杂质较好地限制在SiGe合金基区内，并能有效地提高磷烷对N型掺杂的浓度和外延硅层的生长速率，获得了理想N,P型杂质分布的SiGe/Si HBT外延材料。

GSMBE生长的用于研制HBT的SiGe/Si异质结材料

用GSMBE法生长了Si/SiGe/Si异质结构材料。采用双台面结构制造了SiGe/Si NPN异质结晶体管。在发射结条宽为4μm，面积为4μm×18μm的条件下，其共发射极直流放大倍数为75，截止频率为20GHz。给出了结构设计、材料生长和器件制作工艺。

GSMBE生长的高质量氮化镓材料

使用NH_3作氮源，采用GSMBE方法在(0001)Al_2O_3衬底上生长出了高质量的GaN单晶外延膜。1.2μm厚的GaN外延膜的(0002)X射线双晶衍射峰回摆曲线的半高宽为6'，室温电子迁移率为300cm~2(V·s),背景电子浓度约为3×10~(17)cm~(-3)。

GSMBE原位生长SiGeHBT材料

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低温Si-GSMBE中Si_2H_6的热裂解及对Si生长的影响

为提高外延SiGe/Si HBT材料中Si发射极的生长速率，研究了Si_2H_6预热温度对Si生长速率的影响，结果表明在一很窄的温区内，Si的生长速率提高了一倍，进一步升温Si的生长速率迅速下降。用四极质谱仪对低温Si-GSMBE中Si_2H_6的热裂解过程进行了研究，对该现象做了解释。

GSMBE外延生长GeSi/Sip-n异质结二极管

于2010-11-23批量导入

GSMBE 生长掺杂 Si 及GeSi/Si合金及其电学性质研究

用气态源分子束外延法对Si及GeSi/Si合金进行了N、P型掺杂研究，结果表明，杂质在外延层中的掺入行为取决于生长过程中乙硅烷与相关掺杂气体的竞争吸附与脱附过程，所获得的N型及P型载流子浓度范围分别为1.5×10~(16)～4.0×10~(19)cm~(-3)及1.0×10~(17)～2.0×10~(19)cm~(-3),基于对n型Si外延材料中迁移率与杂质浓度、温度的关系，用Klaassen模型对实验结果进行拟合，分析了不同散射机制，特别是少数载流子电离散射对迁移率的影响。此外，样品的二次离子谱及扩展电阻分析表明，N、P型杂质浓度纵向分布较为均匀，无明显的偏析现象。

GSMBE GaN 膜的电子输运性质研究

用NH_3作氮源的GSMBE方法在晶向为(0001)的α-Al_2O_3衬底上生长非有意掺杂的单晶GaN外延膜，GaN膜呈N型导电，室温时的最高迁移率约为120cm~2/(V·s),相应的非有意掺杂电子浓度为9.1×10~(17)cm~(-3)。对一些GaN膜进行了变温Hall测试，通过电阻率、背景电子浓度以及Hall迁移随温度的变化研究了GaN外延膜的导电机理。结果表明，当温度较低时，以电子在施主中心之间的输运导电为主；当温度较高时，以导带中的自由电子导电为主。