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     

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：     

金刚石膜与Si衬底间过渡层的结构稳定性

用热丝化学汽相沉积(HFCVD)技术在si(111)和si(100)衬底上获得了高质量的金刚石膜。并随着生长时间的增加,利用X射线光电子能谱(XPS)和俄歇电子能谱(AES)研究了过渡层中碳硅化合物组分的变化及其作用。同时提出渐变过渡层:Si/Si_1-xC_x/SiC/Si_yC_1-y/金刚石模型。当组分参量x与y在0.1—0.25之间取值时,用Keating方法给出了系统的稳定结构。 关键词：     

不同剂量C离子注入Si单晶中Si1-xCx合金的形成及其特征

室温下在单晶Si中注入(0.6—1.5)%的C原子,利用高温退火固相外延了Si_1-xC_x合金,研究了不同注入剂量下Si_1-xC_x合金的形成及其特征.如果注入C原子的浓度小于0.6%,在850—950℃退火过程中,C原子容易与注入产生的损伤缺陷结合,难于形成Si_1-xC_x合金相.随注入C原子含量的增加,C原子几乎全部进入晶格位置形成Si_1-xC_{x 关键词： 1-x}C_x合金')" href="#">Si_1-xC_x合金 离子注入 固相外延     

GexSi1-x/Si应变层超晶格的分子束外延生长及其特性研究

在Si(100)衬底上用分子束外延在不同的温度下生长了不同组份的Ge_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。散射等测试方法研究了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、 关键词：     

预注入对Si1-xCx合金形成的影响

室温下在单晶Si中注入(0.6—1.5)at%的C原子,部分样品在C离子注入之前在其中注入²⁹Si⁺离子产生损伤,然后在相同条件下利用高温退火固相外延了Si_1-xC_x合金,研究了预注入对Si_1-xC_x合金形成的影响.如果注入C离子的剂量小于引起Si非晶化的剂量,在950℃退火过程中注入产生的损伤缺陷容易与C原子结合形成缺陷团簇,难于形成Si_1-xC关键词： 离子注入 固相外延 1-xC_x合金')" href="#">Si_1-xC_x合金     

射频磁控溅射法生长MgxZn1-xO薄膜的结构和光学特性

用射频磁控溅射法在80℃的衬底温度下制备出Mg_xZn_1-xO(0≤x ≤030)薄膜.x射线 衍射(XRD)结果表明，Mg_xZn_1-xO薄膜为单相六角纤锌矿结构， 没有形成任何显著 的MgO分离相，Mg_xZn_1-xO薄膜的择优取向平行于与衬底垂直的 c轴；c轴晶格常数随着Mg含量的增加逐渐减小.在Mg_xZn_1-xO薄膜的光透射谱中出现 锐利的吸收边，由透 射谱估算出Mg_xZn_1-xO薄膜的带隙宽度由332eV(x=0)线性地 增加到396eV(x=030). 关键词： xZn_1-xO薄膜')" href="#">Mg_xZn_1-xO薄膜 射频磁控溅射 Mg含量     

Real-time observation of the diffusive motion of 2×2 adlayer formed on Ag(100) nanoparticle facet by nitric acid adsorption

1-x-y Ge_xC_y have been grown on Si(100) substrates by rapid thermal chemical vapor deposition (RTCVD) using C₂H₄ as C source. The composition and microstructure of Si_1-x-yGe_xC_y films were characterized by Auger electron spectroscopy, Raman spectra and Fourier-transform infrared spectroscopy. The results show that lower temperature and higher SiH₄/C₂H₄ flow ratio are helpful in forming the substitutional C and improving the crystal quality. A possible mechanism for C incorporation in Si_1-x-yGe_xC_y layers grown by RTCVD using C₂H₄ is proposed. Received: 26 April 1998 / Accepted: 28 September 1998 / Published online: 24 February 1999     

Highly Efficient pc-LED Phosphors Sr1-xBaxSi2O2N2:Eu2+ (0 x 1) - Crystal Structures and Luminescence Properties Revisited

Due to their excellent luminescence properties in the blue-green to green-yellow spectral region, oxonitridosilicates Sr_1-xBa_xSi₂O₂N₂:Eu²⁺ (0 x 1) are promising conversion materials for application in phosphor-converted high-power LED devices. In order to understand the properties and thus to fully exploit the potential of these materials, detailed knowledge of corresponding (local) crystal structures is indispensable. Detailed insights into real structures have been achieved by combining X-ray diffraction and electron-microscopy methods. A major reason for the excellent luminescence properties of the phases Sr_1-xBa_xSi₂O₂N₂:Eu²⁺ (0 x 1) is the rigid silicate substructure built up of two-dimensionally condensed SiON₃ tetrahedra. The general topology of these layers is analogous for all members. However, there is no complete solid-solution series. Crystal-structure determination was frequently not straightforward because several real-structure effects had to be considered. The relative orientation of the silicate layers and the metal-atom layers inserted between them can differ without changing the chemical composition. As a consequence, polytypes are formed. The differentiation between such closely related structures was only possible by a thorough analysis of crystallographic data. The same applies for phases which differ in their composition as all Sr_1-xBa_xSi₂O₂N₂:Eu²⁺ (0 x 1) phases are very similar. The literature on these compounds is critically discussed with respect to phase analysis and structure determination. Different synthesis routes are reviewed and the results of luminescence investigations are discussed in this contribution. Beyond thermal as well as chemical stability and high transparency, electron-phonon coupling is effectively suppressed in Sr_1-xBa_xSi₂O₂N₂:Eu²⁺ (0 x 1) phases. Therefore, primary UV to blue light (GaN based semiconductor LEDs) is efficiently converted into visible components of the spectrum. Sr_1-xBa_xSi₂O₂N₂:Eu²⁺ (0 x 1) phases are therefore promising oxonitridosilicate phosphors for application in LED industry.     

掺杂的非晶态硅基合金薄膜的高温电子自旋共振研究

本文研究了掺杂(B和P)和未掺杂的a-Si_1-xC_x:H和a-Si_1-xN_x:H膜在高温下的电子自旋共振(ESR)特性。ESR的测量是在温度连续变化的过程中进行的。实验结果表明:掺B的a-Si_1-xC_x:H和a-Si_1-xN_x:H膜的ESR吸收谱,可以分解成两种性质不同的ESR吸收谱的叠加(g₁≈2.005和g₂≈2.010),g₁是硅悬挂键(Si)的贡献,g₂是价带尾态定域化空穴的贡献。随温度的上升,定域化空穴的密度比Si下降得更快。在温度不太高时,定域化空穴的密度远大于Si,但在温度较高时,Si的贡献是主要的。 关键词：     

GaN1-xPx薄膜的结构特性研究

用金属有机物化学气相沉积技术在蓝宝石衬底上外延了高P组分的GaN_1-xP _x 薄膜.利用x射线衍射仪和拉曼光谱仪研究了P对GaN_1-xP_x晶体结构 的影响.研究结果表明：随着P组分比的增加，GaN_1-xP_x（0002）衍射 峰逐渐向小角度移动，即晶格常数变大；与非掺杂GaN相比，GaN_1-xP_x薄 膜的拉曼光谱中出现了4个新的振动模 关键词： 1-xP_x')" href="#">GaN_1-xP_x 金属有机物化学气相沉积 x射线衍射 拉曼光谱     

Preparation, structure and ferromagnetic properties of the nanocrystalline Ti1-xMnxO2 thin films grown by radio frequency magnetron co-sputtering

This paper reported that the Mn-doped TiO2 films were prepared by radio frequency （RF） magnetron cosputtering. X-ray diffraction measurements indicate that the samples are easy to form the futile structure, and the sizes of the crystal grains grow big and big as the Mn concentration increases. X-ray photoemlssion spectroscopy measurements and high resolution transmission electron microscope photographs confirm that the manganese ions have been effectively doped into the TiO2 crystal when the Mn concentration is lower than 21%. The magnetic property measurements show that the Ti1-xMnxO2 （x = 0.21） films are ferromagnetic at room temperature, and the saturation magnetization, coercivity, and saturation field are 16.0 emu/cm^3, 167.5 × 80 A/m and 3740 × 80 A/m at room temperature, respectively. The room-temperature ferromagnetism of the films can be attributed to the new futile Ti1-xMnxO2 structure formed by the substitution of Mn^4＋ for Ti^4＋ into the TiO2 crystal .lattice, and could be explained by O vacancy （Vo）-enhanced ferromagnetism model.     

The optical properties of MgxZnl-xO thin films

Mg_xZn_1-xO thin films have been prepared on silicon substrates by radio frequency magnetron sputtering at 60℃. The thin films have hexagonal wurtzite single-phase structure and a preferred orientation with the c-axis perpendicular to the substrates. The refractive indices of Mg_xZn_1-xO films are studied at room temperature by spectroscopic ellipsometry over the wavelength range of 400--760\,nm at the incident angle of 70℃. Both absorption coefficients and optical band gaps of Mg_xZn_1-xO films are determined by the transmittance spectra. While Mg content is increasing, the absorption edges of Mg_xZn_1-xO films shift to higher energies and band gaps linearly increase from 3.24.eV at x=0 to 3.90\,eV at x=0.30. These results provide important information for the design and modelling of ZnO/ Mg_xZn_1-xO heterostructure optoelectronic devices.     

Si<Subscript>x</Subscript>Ge<Subscript>1-x</Subscript> ultrahigh-vacuum chemical vapor deposition on Si(111)(7×7) from GeH<Subscript>4</Subscript>/Si<Subscript>2</Subscript>H<Subscript>6</Subscript> mixtures

We report the results of a study on ultrahigh-vacuum chemical vapor deposition of Si_xGe_1-x layers on Si(111)(7×7) with GeH₄ and Si₂H₆ mixtures. Using combined scanning tunneling microscopy and X-ray photoelectron spectroscopy, structural properties, the growth kinetics and the composition of the deposited alloys are analyzed as a function of the growth temperature for two different GeH₄:Si₂H₆ mixture ratios. The mutual influence of the precursors is shown by comparing the structures formed during deposition and the sticking coefficients of Si₂H₆ and GeH₄ with results obtained from exposure of Si(111) to the pure gases. Received: 28 July 2002 / Accepted: 2 October 2002 / Published online: 5 February 2003 RID="*" ID="*"Corresponding author. Fax: +49-731/502-5452, E-mail: hubert.rauscher@chemie.uni-ulm.de     

哈斯勒合金Ni-Mn-Ga的马氏体相变和磁增强双向形状记忆效应

通过研究铁磁性金属间化合物Ni_2+xMn_1-xGa(x=-0.1,0,0.08,0.13,0.18,0.2)和Ni_2-xMn_1+x/2Ga_1+x/2(x=-0.1,0,0.04,0.06,0.1)两个系列多晶样品的交流磁化率随温度的变化行为,得到了化合物在不同组分下的马氏体相变温度TM和居里温度T_C.发现随着Ni成分的增加,前者的马氏体相变温度T_m增加,而居里温度T_C降低,后者的马氏体相变温度T_m和居里温度T_C均是先增大后减小.报道了T_m在室温附近的单晶样品Ni₅₂Mn₂₄Ga₂₄的磁场增强双向形状记忆效应.发现伴随着马氏体相变,样品在[001]方向可产生1.2%的收缩.如果在该方向施加1.2T的偏磁场可以使该应变值增大到4.0%.而垂直于[001]方向施加1.2T的偏磁场时,在[001]方向产生1.6%的膨胀.阐明了产生大应变的原因并非相界移动,而是单晶的杂散内应力小和外加磁场通过孪晶界移动使马氏体变体重组的共同结果. 关键词： 形状记忆效应 马氏体相变 2MnGa')" href="#">Ni₂MnGa     

高组份Al值的AlxGa1-x As和AlxGa1-x As/GaAs/AlxGa1-xAs/GaAs多层结构的MOCVD生长

用自制常压MOCVD系统,在半绝缘GaAs衬底上生长高Al组份Al_xGa_1-xAs（其x值达0.83）,和Al_xGa_1-xAs/GaAs/Al_xGa_1-xAs/GaAs多层结构,表面镜面光亮。生长层厚度从几十到十几μm可控,测试表明外延层晶格结构完整,x值调节范围宽,非有意掺杂低,高纯GaAs外延层载流子浓度n_300K=1.7×10¹⁵cm^-3,n_77K=1.4×10¹⁵cm^-3,迁移率μ_300K=5900cmcm²/V.S,μ_77K=55500cm²/V.S。用电子探针,俄歇能谱仪测不出非有意掺杂的杂质,各层间界面清晰平直。 对GaAs,AlGaAs生长层表面缺陷,衬底偏角生长温度及其它生长条件也进行了初步探讨。     

Effect of Cr on hyperfine parameters in a-Fe-Cr-Si-B alloys

Mössbauer studies on a-Fe_80–xCr_xSi₈B₁₂ (x = 0,2,...12) at 5K have been reported. The average hyperfine field and width of P(H) distribution have been analysed by a model which assumes a random distribution of Cr atoms. On assumption that the hyperfine field distribution of Fe atom with r number of Cr nearest neighbours is given by a gaussian with a mean field H_r =H_o - rC₁ + r²C₂; C and C₂ being constants; broad features of Mössbauer spectra are explained.     

退火温度对低温生长MgxZn1－xO薄膜光学性质的影响

用射频磁控溅射法在80℃衬底温度下制备出Mg_xZn_1-xO(x=0.16)薄膜，用X射线衍射(XRD)、光致发光(PL)和透射谱研究了退火温度对Mg_xZn_1-xO薄膜结构和光学性质的影响.测量结果显示，Mg_xZn_1-xO薄膜为单相六角纤锌矿结构，并且具有沿c轴的择优取向；随着退火温度的升高，(002)XRD峰强度、平均晶粒尺寸和紫外PL峰强度增大，(002)XRD峰半高宽(F 关键词： xZn_1-xO薄膜')" href="#">Mg_xZn_1-xO薄膜 射频磁控溅射 退火     

A Mössbauer investigation of the amorphous Tin-Antimony oxide films

The Tin-Antimony oxide films SN_1-xSb_xO₂ (x=0.00-0.66) with thickness about 1100Å have been prepared on glass substrates by CVD and studied by using CEMS and XRD. The broad line widths of Mössbauer spectra and of X-ray diffraction patterns indicate a distribution of the hyperfine parameters due to the distortion of the rutile lattice. A distribution fitting program has been used to evaluate the distribution of quadrupole splitting QS and of isomer shift IS in the samples studied.     

(Pt3Co)1-xNix合金薄膜的结构、磁性和磁光特性研究

采用直流溅射的方法,在Pt₃Co合金靶上加贴Ni片,把（Pt₃Co)_1-xNi_x合金薄膜中非磁性原子与磁性原子的比率从3：1调制到1：1.通过高角X射线衍射谱和磁性的研究,发现<111>织构至少在0.33—0.50的Ni成分范围内不是引起垂直磁各向异性的主要原因.在此基础上研究了(Pt₃Co)_1-xNi_x合金薄膜的磁光特性.研究表明,适量Ni合金化（x=0.43)可以获得较低的(Pt₃Co)_1-xNi_x合金薄膜居里温度,同时保持较高的垂直磁各向异性、较大的矫顽力和蓝波长下较高的Kerr转角,从而为PtCoNi合金薄膜的实用化提供了实验参考. 关键词：