Hg1－xCdxTe分子束外延薄膜晶格参数与组分关系的研究

高分辨率x射线衍射技术被应用于Hg_1-xCd_xTe分子束外延薄膜晶格 参数的测量及其晶格应变状态的研究，研究发现Hg_1-xCd_xTe分子束外延薄膜 内既存在正应变也存在剪切应变. 通过应用晶体弹性理论，对Hg_1-xCd_x Te分子束外延薄膜的应变状态进行了定量的分析与计算，获得了Hg_1-xCd _xTe 分子束外延薄膜在完全弛豫状态下的晶格参数，从而得到了Hg_1-xCd_xTe分子束外延薄膜晶格参数与组分的关系，该关系符合Vegard’s定律，而不是早期研究所给出的Hig gins公式. 研究还发现，根据对称衍射测量所得到的(224)晶面间距，可直接计算出Hg _1-xCd_xTe分子束外延薄膜晶格参数，并用Vegard’s定律确定组分的方 法，可作为估算Hg_1-xCd_xTe分子束外延材料组分的常规技术，其 组分的测量误差在0.01左右. 关键词： 1-xCd_xTe薄膜')" href="#">Hg_1-xCd_xTe薄膜 晶格参数 组分 应变     

Hg1-xCdxTe的低频吸收带

本文对Hg_1-xCd_xTe的低频吸收带,提出另一种解释。把Hg_1-xCd_xTe作为具有0—25％Cd(或Hg)替位杂质的HgTe(或CdTe)晶体,用格林函数计算含有一个Cd(或Hg)的HgTe(或CdTe)双原子链振动谱,进而讨论Hg_1-xCd_xTe混晶振动模的特性,结果表明Hg_1-xCd_xTe在k→0存在频率不趋于零的声学声子,它们有条件吸收远红外波段的光子,形成低频吸收带。它能说明已报道的实验上观察到的低频吸收带的主要特征,并表明对光学声子存在双模行为的其它混晶,在远红外吸收谱中很可能存在类似的低频吸收带。 关键词：     

Sb掺杂Hg1-xCdxTe的光致发光

对不同Sb掺杂浓度Hg_1-xCd_xTe（x≈0.38）样品在3.9—115K的温度范围内进行了光致发光实验测量，观察到与局域激子、带到带和施主受主对有关的辐射复合过程．并用光致发光手段发现Sb掺杂在x≈0.38的Hg_1-xCd_xTe中引入的约30meV的受主能级 关键词：     

Zn0.04Cd0.96Te中深能级的红外光电导谱研究

应用红外光电导谱研究半绝缘p型Zn_0.04Cd_0.96Te中的深能级,在温度从4.2到165K范围内,观察到了位于0.24,0.34,0.38,0.47,0.55和0.80eV处6个光电导响应峰.结合4.2K下光致发光谱的测量结果以及对Zn_xCd_1-xTe中深能级发光光谱、深能级瞬态谱等已有的研究结果,对这些响应峰对应的深能级特性进行了讨论 关键词： xCd_1-xTe')" href="#">Zn_xCd_1-xTe 光电导 杂质 深能级     

Zn1-xCdxS三元混晶的电子结构及光学性质计算与实验验证

基于密度泛函理论的平面波超软赝势法,计算了Zn_1-xCd_xS三元混晶的电子结构和光学性质。计算结果表明,Cd进入ZnS晶格后,禁带宽度变窄,硫空位(V_S)缺陷能级随x值增大逐渐向费米能级移动,在紫外和可见波段的吸收截止波长随着x值增大逐渐红移。采用共沉淀法制备了Zn_1-xCd_xS三元混晶,XRD图谱表明形成了Zn_1-xCd_xS合金相,吸收光谱显示了与理论计算相符的能带和吸收截止边的移动规律,荧光光谱显示与V_S相关的发射峰随x增大逐渐红移,与计算得到的V_S缺陷能级的移动规律相同。     

分子束外延生长的n-Hg1-xCdxTe的磁输运特性

采用迁移率谱和多电子拟合过程相结合的混合电导分析法，对分子束外延（MBE）生长的Hg_1-xCd_xTe材料的变磁场实验数据进行了处理．该方法可以将外延层中体电子对电导的贡献与界面电子的贡献区分开，通过对不同温度下变磁场数据的分析，表明该方法是准确和可靠的，可以成为一种半导体材料和器件的常规电学测试和分析手段 关键词：     

不同邻晶面Hg1-xCdxTe外延薄膜的特性分析

在取向不同的CdTe衬底上用液相外延技术生长了Hg_1-xCd_xTe薄膜，结合金相显微镜、红外显微镜、X射线双晶衍射、红外吸收及Raman光谱等手段分析了不同邻晶面外延层的性质，结果表明，在“近平面”（衬底偏角δ＜0.1°）或“无台阶面”（δ≈1.2°）上生长的外延层的晶格质量及光学性能较好 关键词：     

p-Hg1-xCdxTe材料中轻空穴的性质研究

通过变磁场霍尔测量方法,采用由迁移率谱和多载流子拟合过程相结合的混合电导法,在12-300K范围内,获得了两块分子束外延(MBE)生长的p-Hg_1-xCd_xTe(x=0224)样品中的轻、重空穴以及体电子、表面电子的浓度和迁移率.此外,在实验中,还直接观察到了轻空穴对电导张量分量的贡献.实验值不仅具有明确的物理意义,而且有助于红外探测器模型的建立. 关键词：     

Cd1－xZnxTe晶体的In气氛扩散热处理研究

为了满足辐射探测器件的需要，将生长得到的Cd_1-xZn_xTe晶体在In 气氛下进行退火处理能有效提高晶体的电阻率等性能. 退火处理过程的实质是一个扩散过程 ，因此研究扩散系数与Cd_1-xZn_xTe晶体的性能特别是电阻率变化之 间的关系具有重要的意义. 建立了退火处理过程中Cd_1-xZn_xTe晶体 材料电阻率及导电类型变化与杂质的扩散系数之间关系的模型.结合实验数据，获得了10 关键词： CdZnTe 热处理 In气氛 扩散系数     

Cd1-xZnxTe晶体退火条件的选择及Zn压对退火晶体质量的影响

采用传统Bridgman方法和加入accelerated crucible rotation technique的Bridgman(缩写为ACRT-B)方法生长的Cd_1-xZn_xTe(x=0.04)晶体中存在有点缺陷、位错、杂质和Te沉淀等缺陷.为了减少甚至消除这些缺陷,必须将生长后的CdZnTe晶片在Cd气氛下退火.从Cd-Te和Cd_0.96Zn_0.04Te的PT相图出发,详细讨论了CdZnTe晶体的气固平衡条件,并 关键词： 1-xZn_xTe')" href="#">Cd_1-xZn_xTe 退火 气-固平衡     

Y2(Fe1-xSix)14B的中子衍射研究

Nd₂Fe₁₄B是一种磁能积很高的优良的永磁材料,但在实用上稍嫌它的居里温度低了一点。为了提高它的居里温度,人们曾用某些元素替代其中的一些铁作了尝试。文献[9]及我们最近的实验表明:用硅代替部分铁之后,材料的居里点都获得了提高。本文用中子衍射法研究了Si在Y₂Fe₁₄B中的占位情况,以了解Si对磁性能产生的影响。中子衍射的结果表明:Si择优地占据c,j₁及k₂晶位。最后,用磁交换作用对结果进行了讨论。 关键词：     

Spin rotations in HoxEr1−xFe2 cubic laves compounds

The temperature dependence of the elastic moduli and the Mössbauer effect in Ho_x,Er_1?x, Fe₂ cubic Laves compounds (x, between 0.3 and 0.9) has been investigated in the temperature region where spin rotation occurs. The composition-dependence minima in the elastic moduli, and the Mössbauer effect measurements, were used to determine the boundaries between the various directions of easy magnetization in these compounds. The experimental spin orientation diagram was found to deviate from the predictions of a one-ion model based on the rare-earth ions alone. From the Mössbauer effect measurement it was deduced that in compounds for which a spin reorientation was observed, the spin rotates continuously with temperature between the major axes of the cubic symmetry. This was attributed to the contribution of higher-order magnetocrystalline anisotropy constants. The ΔE effect, measured in external magnetic fields up to 25 kOe, was found to be constant, and relatively small, in the holmium composition range of x = 0.45–1.00 in the Ho_xEr_1?xFe₂; compounds.     

About some transport phenomena in Pb1−xCdxS solid solutions

The paper presents some experimental data concerning Hall effect, Seebeck effect and electrical conductivity in bulk samples of Pb_1?xCd_xS solid solutions, in the temperature range 100–360 K. The results are discussed employing a theoretical model with isotropic isoenergetic surfaces and nonpuadratic dispersion law. At x = 0.06 the dominant mechanism for scattering the charge carriers involves optical phonons below Debye temperature and the state density effective mass is not essentially changed relative to pure lead sulphide.     

Resistivity and critical temperature of (La1-xPrx)0.7Ca0.3MnO3

An empirical formula of the critical temperature that is concentration dependent for polycrystalline (La_1-xPr_x)_0.7Ca_0.3MnO₃ is presented in this paper. With this formula, the temperature dependence of resistance is simulated for various values of x by using the random resistor network model and the Monte Carlo method. The hysteresis effect in \rho -- T curves is reasonably explained. The simulation results are in good agreement with the relevant experimental measurements.     

基于Si-rich SiNx/N-rich SiNy多层膜结构电致发光特性研究

利用等离子体增强化学气相沉积法制备了富硅氮化硅/富氮氮化硅多层膜,并以此氮化硅基多层膜作为有源层构建电致发光器件,在室温下观察到了较强的电致可见发光.在此基础上,研究多层膜结构中作为势垒层的富氮氮化硅层对器件电致发光性质的影响,实验结果表明通过改变势垒层的Si/N组分,调制其势垒高度,器件的电致发光效率可得到显著地提高. 关键词： 电致发光 多层膜 氮化硅     

Radio-frequency (RF) studies of the magneto-dielectric composites: Cr0.75Fe1.25O3 (CRFO)-Fe0.5Cu0.75Ti0.75O3 (FCTO)

This paper concerns a study about the electrical properties of Cr_0.75Fe_1.25O₃ (CRFO)/Fe_0.5Cu_0.75Ti_0.75O₃ (FCTO) magneto-dielectric composites. These compounds were prepared by the conventional solid-state reaction synthesis. The samples synthesized, as well their two-phase composites [Cr_0.75Fe_1.25O₃]_Z-[Fe_0.5Cu_0.75Ti_0.75O₃]_100−Z (Z=17, 34, 50, 66, 83), were characterized by X-ray powder diffraction technique (XRD). Rietveld's method was employed to verify the quantitative phase abundances in the composites’ and their theoretical densities, which were compared with the experimental densities (pycnometer method).To predict the effect of the phases in the composites effective dielectric function (κ), traditional dielectric mixing models such as parallel, series, and Lichtenecker's model were observed. An alternative approach, a sigmoidal fitting function based on the Boltzmann equation, was proposed to fit the experimental data.     

Diode-laser spectroscopy: Temperature dependence of R (0) line in the ν4 band of CH4 perturbed by N2 and O2

In this paper, we present a line profile study of the R (0) line in the ν₄ band of methane diluted in nitrogen and oxygen, from room temperature to 153 K. The measurements were performed over a total pressure range from 14 to 128 mbar. The collisional broadening and narrowing (Dicke effect) coefficients are derived from a fit of the experimental spectra by using the soft and hard collision models, taking into account the Dicke effect. For higher pressures, we have fitted the data with a model taking into account simultaneously the Dicke narrowing and the speed dependence effect. Finally, we have deduced the parameter n of the temperature dependence (inverse power law) of the broadening coefficients for the CH₄-N₂ and CH₄-O₂ gas mixtures.     

Magnetic coupling between Gd and Pr ions and magnetocaloric effect in Gd0.5Pr0.5Al2 compound

In this work, we report the theoretical and experimental investigations on the magnetic and magnetocaloric properties for Gd_0.5Pr_0.5Al₂ compound in different magnetic fields. The magnetization features indicate that Gd_0.5Pr_0.5Al₂ is ferrimagnetic at low temperatures. We also present data from X-ray magnetic circular dichroism (XMCD) experiments for this compound, with which we have confirmed that the magnetic moments of the Pr ions are antiparallel to the magnetic moments of the Gd ions. The magnetocaloric parameters, ΔT_S and ΔS_T, were obtained from calorimetric data and both curves present normal and inverse magnetocaloric effect. A theoretical model for ferrimagnetic coupling, including the crystalline electrical field anisotropy, was used to describe the ΔT_S and ΔS_T experimental results.     

Co1-xNixSb3-ySey热电输运中晶界和点缺陷的耦合散射效应

结合机械合金化与放电等离子烧结工艺制备了Ni和Se共掺的细晶方钴矿化合物Co_1-xNi_xSb_3-ySe_y,研究了晶界和点缺陷的耦合散射效应对CoSb₃热电输运特性的影响.通过Ni掺杂优化载流子浓度提高功率因子.在x=0.1时,功率因子达到最大值1750μWm^-1K^-2(450℃),是没有掺Ni试样的两倍.晶界和点缺陷的耦合散射机理使晶格热导率急剧下降,其中Co_0.9Ni_0.1Sb_2.85Se_0.15的室温晶格热导率降低至1.67Wm^-1K^-1,接近目前单填充效应所能达到的最低值1.6Wm^-1K^-1,其热电优值ZT在450℃时达到最大值0.53.将Callaway-Von Baeyer点缺陷散射模型嵌入到Nan-Birringer有效介质理论模型,对晶界散射和点缺陷散射的耦合效应对热导率的影响进行了定量分析,模型计算与实验结果符合.理论模型计算表明,当晶粒尺寸下降到50nm同时掺杂引入点缺陷散射后,Co_0.9Ni_0.1Sb_2.85Se_0.15的晶格热导率下降到0.8Wm^-1K^-1. 关键词： 3')" href="#">CoSb₃ Ni和Se掺杂 热电性能 耦合散射效应     

PrxLa1-xP5O14的发光理论和浓度效应

本文利用Judd-Ofelt理论求得PrP₅O₁₄晶体的振子强度参数Q₂,比较了计算和实验的振子强度,计算了³P₁,³P₀,¹D₂和¹G₄能级的电偶极和磁偶极辐射跃迁几率及¹D₂→¹G₄和³H₄→³F₄能级对间的多极矩耦合的无辐射迁移几率。讨论了¹D₂能级发射强度的浓度效应。并且,给出¹D₂能级发射强度的表达式和强度随着浓度和单位时间内激发光引起的³H₄到¹D₂跃迁的诱导跃迁几率的变化图。 关键词：