AlN缓冲层对提高硅基GaN薄膜质量的作用机理及其研究进展

AlN作为中间层可以有效提高硅基GaN的晶体质量。本文对于AlN作为形核层和插入层提高GaN晶体质量的机理进行分析和总结，并给出AlN的最佳生长条件。     

Si(111)衬底上多层石墨烯薄膜的外延生长

利用固源分子束外延(SSMBE)技术, 在Si(111)衬底上沉积碳原子外延生长石墨烯薄膜, 通过反射式高能电子衍射(RHEED)、红外吸收谱(FTIR)、拉曼光谱(RAMAN)和X射线吸收精细结构谱(NEXAFS)等手段对不同衬底温度(400、600、700、800℃)生长的薄膜进行结构表征. RAMAN和NEXAFS结果表明: 在800℃下制备的薄膜具有石墨烯的特征, 而 400、600和700℃生长的样品为非晶或多晶碳薄膜. RHEED和FTIR结果表明, 沉积温度在600℃以下时C原子和衬底Si原子没有成键, 而衬底温度提升到700℃以上, 沉积的C原子会先和衬底Si原子反应形成SiC缓冲层, 且在800℃沉积时缓冲层质量较好. 因此在Si衬底上制备石墨烯薄膜需要较高的衬底温度和高质量的SiC缓冲层.     

锰及其硅化物在Si(100)表面的反应外延生长

采用超高真空分子束外延-扫描隧道显微镜(UHVMBE-STM)系统研究了不同温度下锰及其硅化物在Si(100)-2 ×1重构表面上的外延生长情况.实验结果表明当生长过程中衬底温度控制在室温到135℃时,生成大小基本一致的锰纳米团簇;当衬底温度达到210℃时锰与硅开始发生反应,形成硅化物,并有纳米线结构出现;当衬底温度达到330℃时,纳米线完全被棒状物或不规则的三维岛状硅化物取代.随着沉积时衬底温度升高,生成物的成核密度与生长温度的关系与经典的二维岛成核理论相符合.     

Epitaxial Growth of Zinc Sulfide by Atomic Layer Deposition on SiC/Si Hybrid Substrates

Technical Physics Letters - Epitaxial films of zinc sulfide on silicon were obtained by atomic layer deposition (ALD). In order to avoid the interaction between silicon and zinc sulfide, a...     

Planar Hall Effect in Epitaxial Fe Layers on GaAs(001) and GaAs(113)A Substrates

For ferromagnetic layers with in-plane magnetic fields, the longitudinal and transverse resistivities probe the magnetization orientation and its reversal via a spin-orbit-related resistance anisotropy. In the planar Hall effect, we found new contributions in Fe films on GaAs(001) and GaAs(113)A substrates, which cannot be understood within the conventionally used model of the resistance anisotropy. To understand its origin, we adopted a method to determine the orientation of the magnetization from magnetoresistance data. As a result, we were able to identify a symmetric fourfold and a twofold saturated asymmetric in-plane Hall effect for the Fe/GaAs(001) and Fe/GaAs(113)A systems, respectively. Since these new contributions almost perfectly compensate the planar Hall effect based on the resistance anisotropy, we argue about an intrinsic origin of the planar Hall effect in terms of scattering at spin textures within the Fe films.     

Epitaxial growth of PbTe on (100) GaAs substrates

The growth of PbTe films on GaAs by molecular beam epitaxy was studied by reflection high energy diffraction. The strains in the films were investigated by X-ray diffraction. Despite a lattice mismatch of 14.2%, oriented films can be grown up to a thickness of 4000 Å. For thicker films the thermal strain causes cracks if the samples are cooled from growth to liquid-nitrogen temperature.     

Growth of GaAs nanowhisker arrays by magnetron sputtering on Si(111) substrates

The growth of GaAs nanowhisker (NW) arrays on Si(111) substrates by magnetron sputtering is demonstrated. The characteristic NW length is proportional to the effective thickness of a deposited layer and inversely proportional to the transverse whisker size at the top. The results are explained in terms of the diffusion model of NW growth.     

Growth of GaAs Nanowires on Si Substrates Using a Molecular Beam Epitaxy

Au-catalyzed GaAs nanowires were grown on Si substrates by vapor-liquid-solid growth method using a molecular beam epitaxy (MBE). The MBE growth could produce controlled crystalline orientation and uniform diameter along the wire axis of the GaAs nanowires by adjusting growth conditions including growth temperature and V/III flux ratio. Growths of GaAslang001rang as well as GaAslang111rang nanowires were observed by transmission electron microscopy and scanning electron microscopy. Epitaxially grown GaAslang111rang nanowires on a Si(111) substrate were verified through x-ray diffraction out-of-plane 2thetas/omega-scans. A strong room-temperature photoluminescence (PL) was observed from the epitaxially grown GaAslang111rang nanowires on a Si(100) substrate. Results of low-temperature (10 K) PL measurements and current-sensing atomic force microscopy indicated that the GaAs nanowires on a Si substrate were unintentionally doped with Si     

Si(111) 衬底上3C-SiC的超低压低温外延生长

研究了发展一种Si衬底上低温外延生长3C－SiC的方法。采用LPCVD生长系统，以SiH4和C2H4为气源，在超低压（30Pa) ,低温（900℃）的条件下，在Si(111衬底上外延生长出高质量的3C－SiC薄膜材料。采用俄歇能谱（AES），X射线衍射（XRD）和原子力显微镜（AFM）等分析手段研究了SiC薄膜的外延层组分，晶体结构及其表面形貌。AES结果表明薄膜中的Si/C的原子比例符合SiC的理想化学计量比，XRD结果显示了3C－SiC外延薄膜的良好晶体结构，AFM揭示了3C－SiC薄膜的良好的表面形貌。     

Si基Si_(1-x-y)Ge_xC_y合金生长中C的影响

报道了Si基Si1 x yGexCy 合金生长中C对Ge组分和生长速率的抑制作用 ,提出一个Si、Ge、C原子的排列构型 ,从理论上给出了C对Ge组分的抑制度和Ge/C原子比的关系 ,并指出在富Ge情况下C对Ge的抑制作用会趋向于饱和。     

Epitaxial growth of Fe nanodots on SrF2/Si (111)

Fe nanodots were grown on SrF₂ (111) surfaces deposited on Si (111) substrates in a molecular beam epitaxy (MBE) system. The crystallographic and surface morphological characters were studied by reflection high-energy electron diffractometry (RHEED) and atomic force microscopy (AFM). The triangular terraces and step edges of SrF₂ were formed at 600 °C, and its crystallinity was high in quality. Fe (111) layers with thicknesses between 0.5 and 5 nm were grown epitaxially on this SrF₂ layer at room temperature (RT) with the help of electron beam exposure. In 1-nm thick Fe layers deposited at RT, the number density was about 2 × 10¹² cm^− 2. At the end of this report, an epitaxial growth of the SrF₂/Fe/SrF₂ tri-layer on Si (111) is briefly described.     

纳米CeO2颗粒的制备及其对硅晶片（100）和（111）的抛光性能

以硝酸铈和六亚甲基四胺为原料,在微波辐射条件下,使用乙醇/水反应体系,通过均相沉淀法制备了纳米CeO2颗粒,利用X射线衍射仪（XRD）、透射电子显微镜（TEM）、傅里叶转换红外光谱仪（FT-IR）和比表面积测定仪（BET-N2）等手段对样品的成分、物相结构、形貌、颗粒大小以及团聚情况进行了表征.将所制备的纳米CeO2颗粒作为磨料用于硅晶片（100）和（111）的化学机械抛光,用原子力显微镜（AFM）观察抛光表面的微观形貌,测量表面粗糙度,并对抛光表面划痕进行了分析.结果表明,微波辐射以及乙醇/水反应体系均有利于制备出粒径更小、分散性更好的纳米CeO2颗粒,而且微波辐射能够显著加快反应速度;经纳米CeO2磨料抛光的硅晶片（100）和（111）表面非常平整,在2μm×2μm范围内的粗糙度Ra值分别为0.275 nm和0.110 nm,获得了具有亚纳米量级粗糙度的抛光表面.     

硅、锗材料在Si(100)表面的生长研究

利用扫描隧道显微镜和超高真空实验装置系统进行了Si(10 0 )表面生长Si,Ge的实验研究。分析了所生成表面的形貌、结构等物理性质。研究表明 :Si在Si(10 0 )表面的同质生长可以形成纳米结构薄膜。Ge在Si(10 0 )表面生长形成规则的三维小岛。而在Si/Ge/Si(10 0 )多层膜上生长则形成大小二种三维岛。研究表明大岛具有Ge/Si/Ge的壳层结构     

Rapid thermal anneal of arsenic implanted into Si(100) and Si(111)

The effect of the crystallographic orientation on the arsenic distribution in a silicon sample during rapid thermal annealing (RTA) was investigated. An arsenic dose of 6×10¹⁵ cm^-2 was implanted into Si(111) and Si(100) at 30 keV in a commercial ion implanter with mechanical beam scanning. It is found that after “cold” RTA (about 900°C for 16 s) a highly disordered layer is present and there is a difference between arsenic redistribution in Si(111) and Si(100). In the case of “hot” RTA (about 1105°C for 30 s) the amorphous layer created by the heavy arsenic implant is completely regrown, and there is little or no difference in bulk arsenic distributions between both orientations. However, Rutherford backscattering spectrometry measurements show the presence of a multipeak formation in the surface region around the as-implanted peak position. A recently developed multiregion diffusion model for inhomogeneous media is used to fit the experimental profiles.