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．     

Si基β-SiC薄膜外延生长技术研究

采用SiH4-C3H8-H2气体反应体系,通过常压化学气相淀积（APCVD）工艺在P型Si(100)衬底上进行了β-SiC薄膜异质外延生长。利用俄歇电子能谱、SEM及X射线衍射能谱进行了生长薄膜微结构分析。提出并讨论了外延生长β－SiC薄膜的最佳工艺条件及其生长机理。     

Si基Si1—x—yGexCy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。     

原子层淀积 Al2O3薄膜的热稳定性研究

以Al（CH3）3和H2O为反应源，在270℃下用原子层淀积（ALD）技术在Si衬底上生长了Al2O3薄膜．采用X射线衍射（XRD）、X射线光电子能谱（XPS）、原子力显微镜（AFM）和傅立叶变换红外光谱（FTIR）等分析手段对Al2O3薄膜的热稳定性进行了研究．结果表明刚淀积的薄膜中含有少量A-OH基团，高温退火后，Al-OH基团几乎消失，这归因于Al-OH基团之间发生反应而脱水．退火后的薄膜中O和Al元素的相对比例（1．52）比退火前的（1．57）更接近化学计量比的Al2O3．FTIR分析表明，在刚淀积的Al2O3中有少量的-CH3存在，CH3含量会随热处理温度的升高而减少．此外，在高温快速热退火后，Al2O3薄膜的表面平均粗糙度（RMS）明显改善，900℃热退火后其RMS达到1．15nm．     

等离子体增强化学气相淀积a-SiCOF薄膜的稳定性研究

以正硅酸乙酯（TEOS）／C4F8／Ar为气源，采用等离子体增强化学气相淀积（PECVD）方法制备了低价电常数a-SiCOF介质薄膜，并借助X射线光电子能谱（XPS）和傅立叶变换红外光谱（FTIR）对薄膜的化学键结构、热稳定性和抗吸水性进行了研究。     

退火对UHVCVD外延生长锗硅碳三元合金的影响

采用傅立叶红外吸收光谱（FTIR）和X射线衍射（XRD）研究了超高真空化学气相沉积外延生长的Si1-x-yGexCy三元合金的热稳定性，在比较高的退火温度下（950度或以上），Si1-x-yGexCy中的替代位的C逐步形成SiC沉淀，减弱了应变的补偿作用，从而增大了合金中的应变，显示出不同于Si1-x-yGex的驰豫行为。     

氧离子束辅助激光淀积生长ZnO/Si的XPS探究

为了探究ZnO/Si内部化学成分及有关信息,用氧离子束辅助(O+-assisted)脉冲激光淀积(PLD)法在不同实验条件下生长成ZnO/Si(111)样品.利用X射线光电子能谱(XPS)对长成的ZnO/Si异质结构进行了异位测试.通过对O1s峰及其肩状结构进行拟合、分析,得到了原子数密度比n(O)∶n(Zn),进而探究了原子数密度比与生长质量的关系.结果表明,用氧离子束辅助PLD法,可在较低的衬底温度190℃和适当O+束流条件下,生长出正化学比接近于1,且c轴单一取向最佳的ZnO/Si薄膜.用氧离子束辅助PLD淀积法生长ZnO薄膜,可以改善缺氧状况,能提供一个富氧环境.     

以Al2O3为过渡层脉冲激光法制备PZT铁电薄膜

为实现PZT铁电薄膜与半导体衬底的直接集成引入Al2O3为过渡层，首先用真空电子束蒸发法在Si(100)，多昌金刚石（111）衬底上生长约20nm厚的Al2O3过渡层，接着在上述衬底上采用脉冲激光淀积（PLD）法淀积PZT薄膜，衬底温度为350-550℃。X光电子能谱（XPS）测试表明，在高真空下，电子束蒸发Al2O3固态源能获得化学配比接近蒸发源的Al2O3薄膜。X射线衍射（XRD）测试说明，不论衬底是硅还是多晶金刚石，当衬底温度为550℃时，PZT在Al2O3过渡层上呈现（222）取向的焦绿石相结构，当衬底是金刚石时，通过如下工艺：（1）较低温度（350℃）淀积；（2）空气氛围650℃快速退火5min，可以在Al2O3过渡层上获得高度（101）取向的钙钛矿结构的铁电相PZT薄膜，最后AFM测试显示，在硅衬底上，PZT薄膜的表面均方根粗糙度为9.78nm；而在多晶金刚石衬底上，PZT薄膜的表面均方根粗糙度为17.2nm。     

离子束溅射制备Si／Ge多层膜研究

采用离子束溅射方法在Si衬底上制备Si／Ge多层膜，通过改变生长温度、溅射速率等因素得到一系列Si／Ge多层膜样品；通过X射线衍射、Raman散射等表征方法研究薄膜结构与生长条件的关系。在小束流（10mA）、室温条件下制备出界面清晰、周期完整的Si／Ge多层膜。     

外加偏压对未退火Co/n-poly-SiGe肖特基接触特性的影响

采用直流离子束溅射法,在n型单晶硅衬底上淀积Si1-xGex薄膜.俄歇电子谱(AES)测得Si1-xGex薄膜的Ge含量约为0.15.对薄膜进行高温磷扩散后,经XRD测试为多晶态,即得n-poly-Si0.85Ge0.15.在n-poly-Si0.85Ge0.15上溅射一层薄的Co膜,做成Co/n-poly-Si085Ge0.15肖特基结样品.在90～332 K范围对未退火样品做I-V-T测试.研究发现,随着外加偏压增大,表观理想因子缓慢上升,肖特基势垒高度(SBH)下降.基于SBH的不均匀分布建模,得到了二者近似为线性负相关的结论.     

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。     

UHV／CVD外延生长锗硅碳三元合金的应变研究

用超高真空化学气相沉积方法,在Si(100)衬底上生长掺C高达2.2%的Si1-x-yGexCy合金薄膜,外延层质量良好。用高分辨透射电子显微镜,X射线衍射,傅立叶红外吸收光谱以及拉曼光谱对外延层进行了检测。结果表明替代位C的加入,明显缓解了宏观上的应变,但在合金中仍存在着微观应变。     

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     

Energetics of Ge addimers on the Si(1 0 0) and Ge(1 0 0) surfaces: a comparative study

The adsorption energetics of Ge dimers on the (1 0 0) surfaces of Ge and Si has been investigated using the first-principles molecular dynamics method. Four high-symmetry configurations have been considered and fully relaxed. The most stable configuration for Ge dimers on Si(1 0 0) is found to be in the trough between two surface dimer rows, oriented parallel to the substrate Si dimers. These results are consistent with recent experimental studies of the system using the scanning tunneling microscopy (STM), and help to clarify some existing controversies on the interpretation of the STM images. In contrast, for Ge dimers on Ge(1 0 0), the most stable configuration is on top of the substrate dimer row.     

退火对UHVCVD外延生长锗硅碳三元合金的影响

采用傅立叶红外吸收光谱(FTIR)和X射线衍射(XRD)研究了超高真空化学气相沉积外延生长的Si1-x-yGexCy三元合金的热稳定性.在比较高的退火温度下(950℃或以上),Si1-x-yGexCy中的替代位的C逐渐形成SiC沉淀,减弱了应变的补偿作用,从而增大了合金中的应变,显示出不同于Si1-xGex的弛豫行为.     

First principles total energy studies of the adsorption of germane on Ge(001)-c(2 × 4)

We perform first principles total energy calculations to study the energetics, and the atomic structure of the adsorption of germane (GeH₄) molecules on the Ge(001)-c(2 × 4) surface. The adsorption of a GeH₄ unit occurs after its dissociation into a germanium trihydride (GeH₃) and a hydrogen atom and a subsequent decomposition into a germanium dihydride (GeH₂) subunit and H atoms. Consequently, we first consider the adsorption of GeH₂ in two different configurations; the on-dimer and the intra-row geometries. Similar to the adsorption of SiH₂ and GeH₂ on Si(001), it is found that the on-dimer site is more stable than the intra-row geometry by 0.13 eV. However, in the adsorption of a GeH₂ fragment together with two H atoms we find that the intra-row geometry is energetically more favorable, again, similar to the adsorption of SiH₂ and GeH₂ (plus two H atoms) on the Si(001) surface.     

Preparation and characterization of Ge epitaxially grown on nano-structured periodic Si pillars and bars on Si(001) substrate

The selective epitaxial growth of germanium on nano-structured periodic silicon pillars and bars with 360 nm periodicity on Si(001) substrate is studied to evaluate the applicability of nano-heteroepitaxy on the Ge-Si system for different fields of application. It is found that SiO₂ used as masking material plays the key role to influence the strain situation in the Si nano-islands. To analyze this in detail, X-ray diffraction techniques in combination with theoretical simulations based on the kinematical X-ray scattering from laterally strained nano-structures and finite element method (FEM) calculations of the strain field are applied. The oxide related strain in the Si scales about linearly with the thickness of the SiO₂ mask, but FEM simulations supposing a homogeneous stress distribution in the oxide are not sufficient to describe the local strain distribution in the nano-structures. It is demonstrated that the Ge lattice relaxes completely during growth on the Si nano-islands by generation of misfit dislocations at the interface, but a high structural quality of Ge can be achieved by suited growth conditions.     

原子吸收光谱法测定有机锗(Ge-132)中的锗及其杂质

用火焰原子吸收法测定了有机锗(Ge-132)中的锗,线性浓度范围为0～1.25毫克/毫升,相对标准偏差<2%,平均回收率为99.5%。用塞曼石墨炉原子吸收法测定杂质 Pb 和 As,测Pb 时用(NH_4)_2HPO_4+Mg 作改进剂,测 As 时用 Pd 作改进剂,特征质量分别为8.2pg 和8pg,相对标准偏差分别为2.1%和2.2%,还讨论了有关机理问题。     

Monte Carlo backscattering yield (BY) calculations applying continuous slowing down approximation (CSDA) and experimental data

The backscattering yield (BY) is an important factor in elastic peak electron spectroscopy. Monte Carlo (MC) algorithm describing the electron elastic and inelastic backscattering from surfaces is presented applying the continuous slowing down approximation, i.e., an assumption that an electron loses energy continuously along the trajectory length. Energy losses calculations were performed using recently published stopping power (SP) functions, calculated from the experimental optical data by Tanuma et al., and the experimental SP functions published elsewhere. In the MC algorithm, calculating the values of BY, the input parameters are the elastic scattering cross sections and the SP function. The MC calculations were performed at selected energies ranging from 200 to 30 000 eV. Ten elemental solids were considered: Al, Si, Cr, Ni, Cu, Ge, Pd, Ag, Pt, and Au. All MC simulations were performed for normal incidence of the beam on a sample and the backscattered electron emission into negative hemisphere. Results of BY calculations were compared to available experimental data taken from Joy database of electron-solid interactions. In most cases, the results deviate less than 10% from the available experimental data.     

Nucleation of Ge quantum dots on the C-alloyed Si(001) surface

Carbon pre-deposition onto the bare Si(001) surface has been shown to alter the (2×1) surface structure by formation of c(4×4) reconstructed domains containing a high C-concentration. Here we studied by ultra-high vacuum scanning tunneling microscopy the effect of this restructured surface on the initial stages of Ge nucleation by molecular beam epitaxy. Ge is found to form three-dimensional (3D) islands already at sub-monolayer coverage, resulting in a Volmer–Weber growth mode. Strain effects repel Ge adatoms from the C-rich domains, leading to enhanced Ge island formation on the C-free surface regions in between the c(4×4) areas. At a low growth temperature of 350°C, very small three-dimensional islands (3–5 nm in diameter, height 3–4 ML) with a density of nearly 1×10¹² cm⁻² are obtained for only 0.5 ML of Ge. At higher substrate temperatures of approximately 500°C this three-dimensional growth mode is less pronounced, but still evident. The initially nucleated three-dimensional islands define the positions of the larger quantum dots at higher Ge coverage, that exhibit enhanced photoluminescence (PL) properties.