STRUCTURAL DEFECTS AND THEIR ELECTRICAL-ACTIVITY IN GERMANIUM IMPLANTED SILICON

The electrical and structural characteristics of secondary defects in regrown amorphous layers formed in n-type Si(100) with a resistivity of 2 OMEGA cm and 6 OMEGA cm using Ge+ ions, has been studied. The amorphous layers with a thickness of 460 nm are formed by implantation of 1 x 10(15) Ge+ cm-2 at an energy of 400 keV. Both conventional furnace and rapid thermal annealing were used to regrow the amorphous layer and the residual defects have been characterised in terms of their concentration depth distribution and activation energies using C-V and DLTS. Structural information has been obtained from RBS and XTEM. By choosing suitable anneal conditions it is possible to eliminate extended defects, apart from a low concentration of end of range dislocation loops. However, a substantial population of electrically active point defects remain after simple low thermal budget anneals. In a sample implanted with 1 x 10(15) Ge+ cm-2 at 400 keV a region of deep donors approximately 460 nm from the surface is always present When the samples are annealed at higher temperatures (> 850-degrees the total deep donor concentration is reduced by one order of magnitude. Other electrically active defects not observable in the low (750-degrees-C) temperature annealed layers become apparent during anneals at intermediate temperatures.

GROWTH OF HIGH-QUALITY GALLIUM-ARSENIDE ON HF-ETCHED SILICON (001) BY CHEMICAL BEAM EPITAXY

HF etching followed by relatively low temperature (almost-equal-to 600-degrees-C) pretreatment is shown to provide a suitable substrate for the heteroepitaxial growth of GaAs on Si(100) by CBE using TEGa and AsH3 as sources. Rutherford backscattering (RBS), photoluminescence (PL), transmission electron microscopy (TEM), and Raman measurements show the low-defect nature of the GaAs epilayer.

STUDY ON PREPARATION OF GAN AND COSI2 EPITAXIAL-FILMS BY MASS ANALYZED LOW-ENERGY DUAL ION-BEAM EPITAXY

The Mass Analyzed Low Energy Dual Ion Beam Epitaxy (MALE-DIBE) system has been designed and constructed in our laboratory. We believe that the system, which was installed and came into full operation in 1988, is the first facility of this kind. With our system we have carried out studies, for the first time, on compound synthesis of GaN and CoSi2 epitaxial thin films. RHEED and AES results show that GaN films, which were deposited on Si and sapphire substrates, are monocrystalline and of good stoichiometry. To our knowledge, GaN film heteroepitaxially grown on Si. which is more lattice-mismatched than GaN on sapphire, has not been reported before by other authors. RBS and TEM investigations indicated a rather good crystallinity of CoSi2 with a distinct interface between CoSi2 and the Si substrate. The channelling minimum yield chi(min) from the Co profile is approximately 4%. The results showed that the DIBE system with simultaneous arrival of two beams at the target is particularly useful in the formation of novel compounds at a relatively low substrate temperature.

REDUCTION OF CRYSTALLINE DISORDER IN MOLECULAR-BEAM EPITAXY GAAS ON SI BY MEV ION-IMPLANTATION AND SUBSEQUENT ANNEALING

Molecular beam epitaxy GaAs films on Si, with thicknesses ranging from 0.9-2.0-mu-m, were implanted with Si ions at 1.2-2.6 MeV to doses in the range 10(15)-10(16) cm-2. Subsequent rapid infrared thermal annealing was carried out at 850-degrees-C for 15 s in a flowing N2 atmosphere. Crystalline quality was analyzed by using Rutherfold backscattering/channeling technique and Raman scattering spectrometry. The experimental results show that the recrystallization process greatly depends on the dose and energy of implanted ions. Complete recrystallization with better crystalline quality can be obtained under proper implantation and subsequent annealing. In the improved layer the defect density was much lower than in the as-grown layer, especially near the interface.

IMPLANTATION ENERGY SELECTION IN MOLECULAR-BEAM EPITAXY GAAS FILMS ON SI SUBSTRATES

GaAs films made by molecular beam epitaxy with thicknesses ranging from 0.9 to 1.25-mu-m on Si have been implanted with Si ions at 1.2 MeV to dose of 1 x 10(15)/cm2. A rapid infrared thermal annealing and white light annealing were then used for recrystallization. Crystalline quality was analysed by using backscattering channeling technique with Li ion beam of 4.2 MeV. The experimental results show that energy selection is important for obtaining better and uniform recrystallized GaAs epilayers.

射频分子束外延生长AlInGaN四元合金

利用射频等离子体辅助分子束外延(RF-MBE)技术在蓝宝石衬底上外延了铝铟镓氮(AlInGaN)四元合金,通过改变Al源的束流生长了不同组分的AlInGaN四元合金,材料生长过程中采用反射式高能电子衍射(RHEED)进行了在位检测.通过扫描电镜(SEM)、卢瑟福背散射(RBS)、X射线衍射(XRD)和阴极荧光(CL)等测试手段表征了AlInGaN四元合金的结构和光学特性.研究结果表明:在GaN层上生长AlInGaN外延层时,外延膜呈二维生长;当铝炉的温度为920℃时,外延AlInGaN四元合金外延薄膜中Al/In接近4.7,X射线衍射摇摆曲线的半高宽最小为5arcmin,四元合金的阴极荧光发光峰的半高宽为25nm,AlInGaN四元合金外延层具有较好的晶体质量和光学质量.

掺镨GaN薄膜的微结构与光致发光

利用背散射／沟道（RBS／C）技术、原子力显微镜（AFM）和光致发光（PL）谱研究了掺镨GaN薄膜的微结构和可见光发光特性。RBS／C结果表明，注入Pr后，在注入层引入了晶格损伤；注入样品经1050℃退火后，部分损伤得到恢复，但是晶体质量没有恢复到注入前的状态。AFM结果表明，注入Pr后，表面凹凸不平，而且在注入区引起了膨胀，膨胀幅度达到23．368nm左右。PL结果表明，在850—1050℃退火，发光强度按e指数增加；当退火温度达到1050℃，发光强度最强，经过数据拟合可得Pr^3＋的热激活能为5．8eV。

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

中子辐照GaAs的沟道卢瑟福背散射研究

用沟道RBS方法研究了中子辐照GaAs的缺陷在快速退火过程中的恢复行为。结果表明，在10~(14)～10~(17)/cm~2范围内离位原子浓度近似按辐照剂量量级的平方关系增长。中子辐照效应对ψ_(1/2)没有影响。经一定剂量辐照后，退火温度越高，退火时间越长，离位原子的恢复效果越明显。10~(15)/cm~2剂量辐照损伤的恢复激活能E_1 approx=0.23eV,可能对应空位与迁移而来的填隙原子的复合；而10~(17)/cm~2剂量辐照损伤的恢复激活能E_2 approx=0.13eV,对应空位与其附近的填隙原子的复合。

稀土铒和铬离子注入对电机护环钢SCC性能的影响

研究了铒和铬离子高、中能量重迭注入对50Mn18Cr4电机护环钢SCC性能的影响。SCC对比试验结果表明:(1)在QHJ-79标准硝酸盐介质中,离子注入试样的SCC出现时间(t_f)比不经注入试样的延长了6倍以上,致钝和维钝电流密度下降了一个数量级; (2)在阴极充氢条件下,两种试样均对氢致开裂(HIC)不敏感,但离子注入可抑制氢诱发腐蚀。用AES-PRO、RBS、XPS-PRO、EDAX、金相及电化学方法分析讨论了护环钢在QHJ-79标准介质中的SCC机 理和离子注入改善SCC抗力及抗氢锈发腐蚀性能的机制。

MOCVD growth of high quality crack-free GaN on Si(III) substrates

High quality crack free GaN epilayers were grown on Si(111) substrates. Low temperature AlN interlayer grown under low V/III ratio was used to effectively eliminate the formation of micro-cracks. It is found that tensile stress in the GaN epilayer decreases as the N/Al ratio decreases used for AlN interlayer growth. The high optical and structural qualities of the GaN/Si samples were characterized by RBS, PL and XRD measurements. The RT-PL FWHM of the band edge emission is only 39.5meV The XRD FWHM of the GaN/Si sample is 8.2arcmin, which is among the best values ever reported.

快重离子辐照引起Ni/SiO2界面原子混合及相变研究

Ni/SiO2 interface were irradiated at room temperature with 308 MeV Xe ions to 1×1012,5×1012 Xe/cm2 and 853 MeV Pb ions to 5×1011 Pb/cm2,respectively.These samples were analyzed using Rutherford Backscattering Spectrometry(RBS) and X-ray diffraction spectroscopy(XRD),from which the intermixing and phase change were investigated.The obtained results show that both Xe-and Pb-ions could induce diffusion of Ni atoms to SiO2 substrates and result in intermixing of Ni with SiO2.Furthermore,1.0×1012 Xe/cm2 irradiat...中文摘要：在室温下用308 MeV的Xe离子和853 MeV的Pb离子辐照Ni/SiO2样品,用卢瑟福背散射和X射线衍射技术对样品进行了分析。通过分析Ni/SiO2样品中元素成分分布和结构随离子辐照剂量和电子能损的变化,探索了离子辐照在Ni/SiO2样品中引起的界面原子混合与结构相变现象。实验结果显示,Xe和Pb离子辐照均能引起明显的Ni原子向SiO2基体的扩散并导致界面附近Ni,Si和O原子的混合。实验观测到低剂量Xe离子辐照可产生NiSi2相,而高剂量Xe离子辐照则导致了Ni3Si和NiO相的形成。根据热峰模型,Ni原子的扩散和新相的形成可能由沿离子入射路径强电子激发引起的瞬间热峰过程驱动。

Modification of ZnO films under high energy Xe-ion irradiations

ZnO films were deposited on (100) Si substrate by radio frequency magnetron sputtering. These films were irradiated at room temperature with 308 MeV Xe-ions to a fluence of 1.0 x 10(12), 1.0 x 10(13) or 1.0 x 10(14) Xe/cm(2). Then the samples were investigated using RBS, XRD, FESEM and PL analyses. The obtained experimental results showed that the deposited ZnO films were highly c-axis orientated and of high purity, 308 MeV Xe-ion irradiations could not change the c-axis oriented. The topography and PL properties of the ZnO films varied with increasing the Xe-ion irradiation fluence. For 1.0 x 10(13) or 1.0 x 10(14) Xe/cm(2) irradiated samples, surface cracks were observed. Furthermore, it was found that the 1.0 x 10(14) Xe/cm(2) irradiated sample exhibiting the strongest PL ability. The modification of structure and PL properties induced by 308 MeV Xe-ion irradiations were briefly discussed. (C) 2008 Elsevier B.V. All rights reserved.

铝镁尖晶石中He离子注入引起损伤的退火行为研究

利用卢瑟福沟道背散射技术结合表面的原子力显微分析，对注He的铝镁尖晶石晶体的晶格损伤及表面形变随退火温度变化的关系进行了研究.结果表明，不同注入剂量的样品中晶格损伤和表面形变表现出显著不同的退火行为.分析认为造成损伤演化的这种差异与注入的He原子在晶体中不同的聚集状态有关.

高电荷态离子与Si(110)晶面碰撞的沟道效应研究

不同电荷态低速离子(Arq+，Pbq+)轰击Si(110)晶面，测量不同入射角情况下的次级粒子的产额. 通过比较溅射产额与入射角的关系，证实沟道效应的存在. 高电荷态离子与Si相互作用产生的沟道效应说明溅射产额主要是由动能碰撞引起的. 在小角入射条件下，高电荷态离子能够增大溅射产额. 当高电荷态离子以40°—50°入射时，存在势能越高溅射产额越大的势能效应.