超高真空CVD生长锗硅外延层及其双晶X射线衍射研究

利用自行研制的超高真空化学气相沉积系统，在直径３英寸的衬底硅片上生长了锗硅应变外延层，并进行了实时掺杂生长。利用双晶Ｘ射线的衍射技术测试了餐延层，确定外延层的组分怀晶体质量，并利用二次离子质谱仪进行了纵向组分分布剖 析，利用扩展电阻仪确定外延层的电学特性，研究了锗硅应变外延层的生长特性和材料特性，生长速率随锗组分的增加而降低，以氢气为载气的硼烷对锗硅合金的生长速率有促进作用。还通过生长锗 组分渐变     

超高真空CVD生长锗硅外延层的应变弛豫

用超高真空ＣＶＤ技术在７８０℃生长了锗硅外延层及组分渐变缓冲层,并利用双晶Ｘ射线衍射仪研究了缓冲层对外延层晶体质量的影响。结果表明,衬底与外延之间生长了组分几乎线性渐变的缓冲层,提高了外延层的晶体质量     

超高真空CVD生长锗硅外延层的应变驰豫

用超高真空ＣＶＤ技术在７８０℃生长了锗硅外延层及组分渐变缓冲层，并利用双晶Ｘ射线衍射仪研究了缓冲对外延层晶体质量的影响。结果表明，衬底与外延之间生长了组分几乎线性渐变的缓冲层，提高了外延层的晶体质量。     

锗硅碳合金中碳的应变缓解效应研究

SiGeC三元合金成为近年来人们研究的热点之一。处于替代位置的碳可以缓解SiGe合金的应变,同时调节其能带,在能带工程上提供了更大的灵活性。本文利用UHV/CVD技术生长了掺碳达2.2%的锗硅碳合金,获得了良好的外延层质量,并对碳的应变缓解效应进行了研究。     

锗硅碳合金中碳的应变缓解效应研究

ＳｉＧｅＣ三元合金成为近年来人们研究的热点之一。处于替代位置的碳可以缓解ＳｉＧｅ合金的应变,同时调节其能带,在能带工程上提供了更大的灵活性。本文利用ＵＨＶ／ＣＶＤ技术生长了掺碳达２．２％的锗硅碳合金,获得了良好的外延层质量,并对碳的应变缓解效应进行了研究。     

SiGe薄膜的RPCVD负载影响及特性研究

利用RPCVD系统,在150mm(100)硅片衬底上了制备出高质量锗硅合金薄膜,研究了温度和锗烷流量对薄膜生长速率与合金中锗浓度的影响,并对薄膜进行了掺杂处理。分别利用高分辨透射电子显微镜、高分辨X射线衍射、原子力显微镜、二次离子质谱表征了薄膜特性。结果表明,通过克服RPCVD系统中外延层高缺陷密度、掺杂控制困难等缺点,制备出高质量的SiGe薄膜。     

外延生长碳化硅-石墨烯薄膜的制备及表征研究

石墨烯作为一种碳原子所组成的二维蜂窝状结构晶体,具有诸多优异的特性,从而倍受全世界科学工作者的关注。在碳化硅衬底上外延生长石墨烯是实现石墨烯在微电子领域中应用的最有效途径之一。利用感应加热的高温CVD设备,先在4H-Si C衬底上外延生长一层2~10μm厚的碳化硅,然后直接再在外延碳化硅上原位外延生长石墨烯。实现外延碳化硅-石墨烯的连续生长,从而减少氢气刻蚀带来的晶格缺陷和表面硅富集严重削减现象,并使低成本制备碳化硅上的石墨烯成为可能。通过拉曼光谱、扫描电子显微镜及X射线光电子能谱等表征,验证了该方法生长的石墨烯具有较好的晶体质量。     

UHV/CVD生长锗硅材料的偏析现象

本文对利用超高真空CVD方法生长的Si1-xGex合金外延层中的锗表面分布情况和Ge在界面偏析现象进行了深入的研究.通过XPS和SIMS图谱的研究,指出表面由于锗的偏析,造成锗在体内和表面的含量不同,在低温时生长锗硅合金,表面氢原子的吸附可有效地抑制锗的偏析,但随着温度的升高,氢的脱附造成锗的偏析现象更加明显.     

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.     

200mmBCD器件用硅外延片制备技术研究

本文涉及200 mm BCD(Bipolar-CMOS-DMOS)器件用硅外延片制备技术，通过结合BCD工艺用外延材料的特性要求，从外延图形漂移、外延层均匀性、表面缺陷等参数指标，分析了衬底埋层浓度、生长温度、生长速率、缓冲层结构等工艺参数对外延参数的影响，优化了BCD工艺用硅外延片的制备方法。本文采用常压化学气相沉积(CVD)技术制备了BCD工艺用200 mm硅(Si)外延材料，通过Hg-CV、SP1及SRP对埋层外延片进行测试分析，实验结果验证了工艺设计的正确性和有效性，提升了大尺寸埋层外延制备技术的产业化水平。     

GaAS/Si(100)异质外延4°偏角衬底对外延层结晶质量的提高(英文)

用低压金属有机物化学汽相沉积法(MOCVD)在Si(100)无偏角和Si(100)4°偏角衬底上外延生长GaAs层。异质外延采用两步生长法,并分别优化了两种衬底上的非晶低温缓冲层的生长条件。用X射线双晶衍射(XRD)和透射电子显微镜(TEM)对两种衬底上的GaAs外延层进行了结构表征,其中Si(100)4°偏角衬底上1.8μm厚GaAs的(004)面XRD衍射半高全宽338 arcsec,同比在无偏角衬底上的半高全宽为494arcsec,TEM图片显示4°偏角衬底上外延层中的位错密度大大降低。     

超高真空CVD生长的Si1-xGex合金组分变化与表面偏析现象

系统分析了利用超高真空CVD技术在Si衬底上外延Si1-xGex 合金的体内组分分布情况和Ge的表面偏析现象。用SIMS对Si和Ge的组分作了深度剖析。在生长过程中 ,组分均匀 ,在表面Ge浓度减小 ,Si浓度没有明显变化。在不经HF酸清洗和在HF酸中去掉表面自然氧化层的两种情况下 ,用XPS分别对外延层表面进行了定量分析 ,得到Ge的表面偏析与表面自然氧化相关的结论     

500℃下利用UHV/CVD在Si衬底上直接生长近平面Si0.5Ge0.5层

利用UHV/CVD系统,在一个相对较低的温度500℃下,研究了Si1-xGex层中的Ge含量与生长条件之间的关系,此时的Si1-xGex层处于一种亚稳的状态.并直接在Si衬底上生长制备了10个周期的3.0 nm-Si0.5Ge0.5/3.4 nm-Si多量子阱.拉曼谱、高分辨显微电镜和光荧光谱对其结构和光学性能进行的表征表明这种相对较厚的Si0.5Ge0.5/Si多量子阱结构基本上仍是近平面生长的,内部没有位错,其在电学和光学器件上具有潜在的应用.     

The dependence of GexSi1-x epitaxial growth on GeH4 flow using chemical vapour deposition

GexSi1-x epilayers were grown at 700–900°C by atmospheric pressure chemical vapour deposition. GexSi1-x, Si and Ge growth rates as functions of GeH4 flow are considered separately to investigate how the growth of the epilayers is enhanced. Arrhenius plots of Si and Ge incorporation in the GexSi1-x growth show the activation energies associated with the growth rates are about 1.2 eV for silicon and 0.4 eV for germanium, indicating that Si growth is limited by surface kinetics and Ge growth is limited by mass transport. A model based on this idea is proposed and used to simulate the growth of GexSi1-x. The calculation and experiment are in good agreement. Growth rate and film composition increase monotonically with growth pressure; both observations are explained by the model. This revised version was published online in August 2006 with corrections to the Cover Date.     

Chloride vapor-phase epitaxy of gallium nitride on silicon: Structural and luminescent characteristics of epilayers

The structure and luminescent properties of gallium nitride (GaN) epilayers grown by hydride-chloride vapor-phase epitaxy (HVPE) in a hydrogen or argon atmosphere on 2-inch Si(111) substrates with AlN buffer layers have been studied. The replacement of hydrogen atmosphere by argon for the HVPE growth of GaN leads to a decrease in the epilayer surface roughness. The ratio of intensities of the donor-acceptor and exciton bands in the luminescence spectrum decreases with decreasing growth temperature. For the best samples of GaN epilayers, the halfwidth (FWHM) of the X-ray rocking curve for the (0002) reflection was 420 sec of arc, and the FWHM of the band of exciton emission at 77 K was 48 meV.     

Al/Si contacting of ultra-shallow epitaxially grown Si and SiGe junctions

Ultra-shallow diodes have been fabricated by epitaxially growing thin layers of highly doped Si or strained SiGe on silicon substrate wafers and contacting with Al/1%Si. Ideal diode I –V characteristics were achieved for both n⁺p and p⁺n junctions as shallow as 20 nm. The formation of silicon precipitates on the contact surface as a result of alloying after metallization was found to be impeded by increasing the Ge content of the epitaxially grown layer. For a concentration of 27%, no precipitates were observed.     

Raman scattering studies of ultrashallow Sb implants in strained Si

Sheet resistance (R _s) reductions are presented for antimony doped layers in strained Si. We use micro-Raman spectroscopy to characterise the impact of a low energy (2 keV) Sb implantation into a thin strained Si layer on the crystalline quality and resultant stress in the strained Si. The use of 325 nm UV laser light enables us to extract information from the top ∼9 nm of the strained Si layer. Prior to implantation the Si layer is fully strained with a tensile stress value ∼1.41 GPa, in agreement with the calculated theoretical maximum on a strain relaxed buffer with 17% Ge content. There is a clear decrease in the intensity of the Si Raman signal following Sb implantation. The lattice damage and lattice recovery achieved by subsequent rapid thermal anneal (RTA) is quantified using the amplitude and full width at half maximum (FWHM) of the crystalline Si peak. The shift of the Raman Si peak is a key parameter in the interpretation of the spectra. The ion-implanted sample is studied in terms of a phonon coherence length confinement model. Carrier concentration effects are seen to play a role in the Raman shift following electrical activation of the Sb atoms by RTA.     

Ge组分渐变的Si1-x-yGexCy薄膜的制备

用化学气相淀积方法在Si（100）衬底上外延生长了Ge组分最高约0．40的组分渐变的Si1-x-yGexCy合金薄膜,研究了生长温度等工艺参数的影响．结果表明,生长温度和C2H4分压的提高均导致薄膜中碳组分的增加和合金薄膜晶格常数的减小,这表明外延薄膜中的C主要以替位式存在．C掺入量的变化可有效地调节薄膜的禁带宽度,而提高生长温度有助于改善Si1-x-yGexCy薄膜的的晶体质量．组分渐变的Si1-x-yGexCy合金薄膜包括由因衬底中Si原子扩散至表面与GeH4．C2H4反应而生成的Ni1-x-yGexCy外延层和由Ni1-x-yGexCy外延层中Ge原子向衬底方向扩散而形成的Ni1-xGex层．     

Growth of high Ge content SiGe on (110) oriented Si wafers

Growth of high (above 40%) Ge content SiGe by applying silane and dichlorosilane as Si precursors on (110) Si is investigated. In the case of silane based processes Ge concentration is ~ 20% higher, whereas for dichlorosilane based processes it is ~ 30% lower on (110) Si compared to (100) Si. The morphology of the grown layers is found to be dependent on Ge concentration, layer thickness and process temperature. Use of optimized deposition parameters and adequate thickness results in high quality strained SiGe layers. Integration of high Ge content SiGe layers in multiple gate filed-effect transistor structures shows the expected differences in Ge content on the different Si planes forming Si fin. These differences can be avoided by adjusting the fin orientation on the Si wafer resulting in equal planes on the fin's top and sidewalls. When the investigated SiGe layers are incorporated in the buried channel field effect transistor structures on (110) Si wafers a significant thickening at the active windows edge is observed. It is speculated that this effect is connected with elastic SiGe relaxation caused by a non optimized process temperature.     

Ge and GexSi1 − x islands formation on GexSi1 − x solid solution surface

Critical thicknesses of 2D to 3D growth and morphological ‘hut’-‘dome’ cluster transitions in Ge layers were measured. In comparison with the growth on the pure Si(100) surface, a decrease in the critical thicknesses of 2D-3D and hut-dome transitions was observed and accounted for by the accumulation of elastic strains as Ge content or thickness of the GeSi solid solution increased. The density and size of Ge nanoclusters were determined depending on the solid solution composition. The presence of a thin strained layer of the GeSi solid solution caused not only the changes in critical thicknesses of the transitions, but also affected the properties of the germanium nanocluster array.