GexSi1-x/Si超晶格的X射线小角衍射分析

用分子束外延生长了23周期的Ge_xSi_1-x/Si超晶格,用计算机控制的衍射仪(CuK_a辐射)测量了X射线衍射曲线,共观察到13级超晶格结构的衍射峰。超晶格的周期和Ge平均含量可以根据考虑折射修正的布喇格定律得出。用光学多层膜反射理论分析衍射曲线可以确定超晶格的结构参数,第2级衍射峰与第一级峰的强度比对应于超晶格两种材料的相对厚度变化非常灵敏,通过比较实验和计算的I₂/I₁值,可以确定Si,Ge_xSi_1-x层的厚度以及合金组份x。用光学多层膜反射理谁计算得到的衍射曲线与实验曲线趋于一致。 关键词：     

高完整GexSi1-x/Si应变超晶格的X射线双晶衍射研究

本文用X射线双晶衍射技术对分子束外延生长的Ge_xSi_1-x/Si应变超晶格的结构参数进行研究,分别采用X射线运动学理论和动力学理论对超晶格的双晶摆动曲线进行计算模拟,得出超晶格的全部结构参数;并对这两种理论计算模拟的结果进行比较,发现这两种理论计算的结果基本一致,只是在细微结构上略有差别,对高完整Ge_xSi_1-x/Si超晶格,用动力学理论计算的曲线更接近于实验曲线。 关键词：     

高能电子衍射研究H钝化偏角Si衬底上Si,GexSi1-x的分子束外延生长模式

用高能电子衍射(RHEED)研究H钝化偏角Si衬底上Si,Ge_xSi_1-x材料的分子束外延(MBE)生长模式,发现经低温处理的H钝化Si衬底上要经过10nm左右的Si生长才能获得比较平整的表面.Si,Ge_xSi_1-x外延时的稳定表面均以双原子台阶为主,双原子台阶与单原子台阶并存的结构.Si双原子台阶上的Si二聚体列(dimerrow)取向垂直于台阶边缘,而Ge_xSi_1-x双原 关键词：     

GexSi1-x/Si超晶格的俄歇深度剖面分析

用氩离子刻蚀和俄歇电子能谱测量Ge_xSi_1-x/Si应变层超晶格的成分深度分布,得到Ge,Si两种成分随深度的周期性变化,在二次电子象中观察到刻蚀坑边缘的明暗交替的周期性结构。讨论了用俄歇深度剖面分布作超晶格结构分析的特点及其局限性。 关键词：     

(Si)n/(Ge)n超晶格几何结构

本文用Keating模型计算了Si_1-xGe_x(x=0—1)作衬底、沿(100)方向生长的(Si)_n/(Ge)_n(n=1—6)应力超晶格的几何结构,并讨论了衬底对超晶格生长的影响,计算结果发现对于(Si)_n/(Ge)_n超晶格,用适当的Si_1-xGe_x作衬底有利于超晶格的生长。 关键词：     

Ge_xSi_1-x_/Si应变层超晶格的分子束外延生长及其特性研究

在 Si (l00) 衬底上用分子束外延在不同的温度下生长了不同组份的GeGe_xSi_1-x_/Si 应变层超晶格.用反射式高能电子衍射、x 射线双晶衍射、卢瑟福背散射、透射电子显微镜以及Raman散射等侧试方法研究了Ge Ge_xSi_1-x_/Si超晶格的生长及其结构特性. 结果表明, 对不同合金组份的超晶格, 其最佳生长温度不同. x值小, 生长温度高; 反之, 则要求生长温度低. 对于x为0. 1-0. 6 , 在400-600℃ 的生长温度范围能够长成界面平整、晶格完好和周期均匀的GeGe_xSi_1-x_/Si应变层超晶格. 关键词：     

用深能级瞬态谱方法研究赝晶Si/Ge0.25Si0.75/Si单量子阱的价带偏移

应变的Ge_xSi_1-x层和未应变的硅层间的能带偏移主要是价带偏移。量子阱中载流子的热发射能与界面的能带偏移有着密切的关系。本文用深能级瞬态谱(DLTS)研究分子束外延生长的p型Si/Ge_0.25Si_0.75/Si单量子阱的价带偏移,阱宽为15nm,考虑到电场的影响和量子阱中第一子能级的位置,对从DLTS得到的热发射能进行适当的修正,可以计算出Si/Ge_0.25Si_0.75/S 关键词：     

GexSi1-x合金中的键长及其对电子能带结构的影响

采用经验紧束缚理论，以类似闪锌矿结构的晶体模型模拟Ge_xSi_1-x合金，根据总能最小原则计算了Ge_xSi_1-x合金中的键长及点阵常数．同时以紧束缚方法计算了原子位置发生弛豫前后的电子能带结构，并与虚晶近似下的计算结果进行了比较．计算结果表明，Ge_xSi_1-x合金中的键长基本上与合金组分无关，各自接近于Ｇｅ，Ｓｉ晶体中的键长，与广延ｘ射线吸收精细结构（ＥＸＡＦＳ）测量结果符合得 关键词：     

MoxGe1-x,MoxSi1-x薄膜的非晶形成成份及超导转变温度

用直流吸气溅射法在液氮冷底板上分别制备了Mo_xGe_1-x,Mo_xSi_1-x的薄膜。其形成非晶的成份分别为Ge>22at%,Si>18at％。超导转变临界温度T_c在非晶状态下随着Ge,Si的含量增加而下降(约6—3K)。非晶Mo₇₇Ge₂₃膜的晶化温度为780℃,而非晶Mo₇₈Si₂₂膜的晶化温度为480℃。 关键词：     

Na3Zr2-xInxSi2-xP1+xO12系统的组成、结构和离子电导的关系

用固相反应、X射线衍射、金相显微镜观察、测定比热和复平面阻抗谱的方法研究了Na₃Zr_2-xIn_xSi_2-xP_1+xO₁₂系统。在此系统中存在两种固溶体:单斜固溶体(0≤x<0.8)和三方固溶体(0.8≤x≤1.8)。即从x=0.8的组成开始,NASICON型Na₃Zr_2-xIn_xSi_2-x 关键词：     

An effective compliant substrate for low-dislocation relaxed Si1-xGex growth

An effective compliant substrate for Si_1-xGe_x growth is presented. A silicon-on-insulator substrate was implanted with B and O forming 20 wt % borosilicate glass within the SiO₂. The addition of the borosilicate glass to the buried oxide acted to reduce the viscosity at the growth temperature of Si_1-xGe_x, promoting the in situ elastic deformation of the thin Si (∼20 nm) layer on the insulator. The sharing of the misfit between the Si and the Si_1-xGe_x layers was observed and quantified by double-axis X-ray diffraction. In addition, the material quality was assessed using cross-sectional transmission electron microscopy, photoluminescence and etch pit density measurements. No misfit dislocations were observed in the partially relaxed 150-nm Si_0.75Ge_0.25 sample as-grown on a 20% borosilicate glass substrate. The threading dislocation density was estimated at 2×10⁴ cm^-2 for 500-nm Si_0.75Ge_0.25 grown on the 20% borosilicate glass substrate. This method may be used to prepare compliant substrates for the growth of low-dislocation relaxed SiGe layers. Received: 4 January 2001 / Accepted: 30 May 2001 / Published online: 17 October 2001     

ELECTROLUMINESCENCE SPECTRA OF GexSi1-x/Si SINGLE QUANTUM WELL

The electroluminescence of Ge_xSi_1-x/Si single quantum well was measured at temper-atures above room temperature along the growth direction and the direction normal to it. TO and NP peaks were resolved.     

Dopant diffusion and segregation in semiconductor heterostructures: Part 2. B in GexSi1-x/Si structures

x Si_1-x/Si heterostructures have been obtained. Here the chemical effects seem to be of less importance. The Fermi-level effect determines the ionized boron solubilities in Ge_xSi_1-x and in Si, as well as the thermal equilibrium concentration of the singly-positively-charged crystal self-interstitials I⁺ which governs the boron diffusion process. The junction carrier concentration affects the concentration of I⁺ and solubility of B in the region and hence controls B diffusion across the heterojunction. Received: 20 August 1998/Accepted: 23 September 1998     

Observation of strain relaxation in Si1-xGex layers by optical and electrical characterisation of a Schottky junction

We have studied the effect of the strain relaxation on the band-edge alignments in a Pt/p-Si_1-xGe_x Schottky junction with x=0.14 by internal photoemission spectroscopy and current–voltage measurements. We have shown that the variations in the band-edge alignments can be observed directly by measuring the optical and electrical properties of a simple Schottky junction. The strain in the Si_1-xGe_x layer has been partially relaxed by thermal treatments at two different temperatures. The degree of relaxation and other structural changes have been determined by a high-resolution X-ray diffractometer. Both optical and electrical techniques have shown that the barrier height of the Pt/Si_0.86Ge_0.14 junction increases with the amount of relaxation in the Si_1-xGe_x layer. This shows that the valence-band edge of the Si_1-xGe_x layer moves away from the Fermi level of the Pt/Si_1-xGe_x junction. The band-edge movement results from the increase in the band gap of the Si_1-xGe_x layer after the strain relaxation. This result agrees with the theoretical predictions for the strain-induced effects on the Si_1-xGe_x band structure. Received: 18 October 2000 / Accepted: 19 December 2000 / Published online: 23 March 2001     

p型GexSi1-x/Si多量子阱的红外吸收及其分析

通过测量GeSi多量子阱的红外谱，同时观察到了相应于量子阱内重空穴基态HH1到重空穴激发态HH1、轻空穴激发态LH1和自旋分裂带SO及连续态间的跃迁吸收．测量了GeSi多量子阱探测器的正入射光电流谱，看到了明显的光响应峰．理论计算中计及了轻、重和自旋分裂带间的耦合及能带的非抛物性，并自洽考虑了哈特里势和交换相关势．与实验结果比较，认为带之间的耦合，使子带间的跃迁情况变得复杂，是正入射吸收产生的原因 关键词：