玻璃中CuCl_xBr_(1-x)(x=0—1)胶体的激子光谱

一个物质未必具有大晶体一样的周期结构,但只要形成了似晶体的集团,也可以显示出晶体一样的基本光吸收。本工作研究了含CuCl_xBr_(1-x)(x=0—1)胶体的玻璃制备和光吸收性质。实验结果表明玻璃中达到一定大小的CuCl,CuCl_xBr_(1-x)和CuBr胶体粒子也可显示出与相应大块晶体相同的激子吸收光谱,玻璃具有和相应晶体相同的紫外吸收限。     

CsPbxSn1-xBr3/a-ZrP复合材料的光学性能及其在白色发光二极管中的应用

钙钛矿量子点(PQDs)由于具有高量子效率、可调节带隙、高色纯度及低成本等优点,在光电领域具有良好的应用前景。然而,其较差的稳定性阻碍了钙钛矿量子点的应用。本文在室温条件下合成了CsPb_xSn_1-xBr₃/a-ZrPPQDs,与传统CsPbBr₃PQDs对比,具有更好的光学性能及稳定性。由于a-ZrP对于Pb²⁺选择吸附性的固有特性以及与Cs⁺离子交换的能力,促进了量子点在a-ZrP表面的吸附锚定。因此,合成的CsPb_xSn_1-xBr₃/a-ZrPPQDs具有更高的激子结合能和更强的环境稳定性。该复合材料为生产稳定高效的钙钛矿量子点提供了一种可行的方法,并表明CsPb_xSn_1-xBr₃/a-ZrPPQDs是一种高效的下转换荧光材料,可用于高效发光二极管的制备。     

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。     

Zn1-xMnxSe的低温磁化率和自旋玻璃现象

用超导量子干涉器(SQUID)磁强计对稀释磁性半导体Zn_1-xMn_xSe(0.1≤x≤0.50)的低温低场直流磁化率作了测量,测量温度从4.2K到30K,测量磁场为15Oe。当x≥0.30时,从磁化率-温度曲线的浑圆峰值,观察到了自旋玻璃的转变。自旋玻璃的转变温度T_f,对x=0.30,0.40,0.50,分别为10.5K,16K,19.5K。给出了顺磁相和自旋玻璃相的相图。比较了Zn_1-xMn_xSe和Cd_1-xMn_xSe的自旋玻璃转变温度,发现对同样的Mn离子浓度,Zn_1-xMn_xSe的T_f高于Cd_1-xMn_xSe的T_f,用交换作用的理论作了讨论。 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：     

Ge(001)衬底上分子束外延生长高质量的Ge1-xSnx合金

Ge_1-xSn_x是一种新型IV族合金材料, 在光子学和微电子学器件研制中具有重要应用前景. 本文使用低温分子束外延(MBE)法, 在Ge(001)衬底上生长高质量的Ge_1-xSn_x合金, 组分x分别为1.5%, 2.4%, 2.8%, 5.3%和14%, 采用高分辨X射线衍射(HR-XRD)、卢瑟福背散射谱(RBS) 和透射电子显微镜(TEM)等方法表征Ge_1-xSn_x合金的材料质量. 对于低Sn组分(x≤ 5.3%)的样品, Ge_1-xSn_x合金的晶体质量非常好, RBS的沟道/随机产额比(χ_min)只有5.0%, HR-XRD曲线中Ge_1-xSn_x衍射峰的半高全宽(FWHM)仅100' 左右. 对于x=14%的样品, Ge_1-xSn_x合金的晶体质量相对差一些, FWHM=264.6'. 关键词： 锗锡合金 锗 分子束外延     

GdxY1-xCa4O(BO3)3晶体非临界相位匹配波长的研究

根据YCa₄O(BO₃)₃(YCOB),GdCa₄O(BO₃)₃(GdCOB)的折射率拟合方程,分析了Gd_xY_1-xCOB可实现非临界相位匹配的波长范围.利用704-5型光参量放大器,测量了非临界相位匹配波长随组分x的变化关系. 关键词： xY_1-xCOB晶体')" href="#">Gd_xY_1-xCOB晶体 非临界相位匹配波长     

铁电单晶(KxNa1-x)0.4(SryBa1-y)0.8Nb2O6的光学性质和线性电光效应

本文介绍铁电单晶(K_xNa_1-x)_0.4(Sr_yBa_1-y)_0.8Nb₂O₆的光学性质和线性电光效应的测量。实验结果表明,这种晶体具有较大的光学双折射,透光范围由4000?到5.6μm。晶体具有低的线性电光调制的半波电压,其电光调制价值指数n₀³·γ_c高达730×10 关键词：     

AgxCu50-xZr50非晶态合金及其晶化

采用高频熔炼后的真空单辊急冷技术制备了Ag_xCu_50-xZr₅₀金属玻璃,发现在x<12的范围内都可得到完全的非晶态。测量了x=2,4,6和10的Ag_xCu_50-xZr₅₀金属玻璃的玻璃转变温度和晶化温度,并采用Kissinger方法测定了晶化激活能E_a。发现在金属玻璃Ag_xCu_50-xZr_{50关键词：}     

R3(Fe1-xCox)29-yCry(R=Gd,Sm)化合物相稳定性研究

在制备出Gd₃(Fe_1-xCo_x)_29-yCr_{y化合物基础上，成功制备出Sm3(Fe1-xCox)29 -yCry化合物，通过x射线衍射和热磁分析对R3(Fe1-x< /sub>Co x)29-yCry 关键词： 3(Fe1-xCox)29-yCry化合物')" href="#">R3(Fe1-xCox)29-yCry化合物 相结构 单轴磁晶各向异性}     

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：     

Photoluminescence and transmission spectra of nanocrystalline GaAs（1-x）Sbx embedded in silica films

The composite films of the nanocrystMline GaAs（1-x）Sbx-SiO2 have been successfully deposited on glass and GaSb substrates by radio frequency magnetron co-sputtering. The 10K photoluminescence （PL） properties of the nanocrystalline GaAs（1-x）Sbx indicated that the PL peaks of the GaAs（1-x）Sbx nanocrystals follow the quantum confinement model very closely. Optical transmittance spectra showed that there is a large blue shift of optical absorption edge in nanocrystMline GaAs（1-x）Sbx-SiO2 composite films, as compared with that of the corresponding bulk semiconductor, which is due to the quantum confinement effect.     

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.     

Hg1-xCdxTe禁带以上的本征光吸收

讨论了HgCdTe三元半导体在能量大于禁带宽度范围内的本征吸收光谱。经过分析比较实验数据,Kane理论结果以及几种经验公式,指出Anderson从Kane模型获得的理论公式及褚君浩等从实验结果得出的经验公式,最符合HgCdTe禁带以上本征光吸收行为。文中还就外延薄膜样品的本征吸收进行了讨论。 关键词：     

白宝石衬底上生长的MgxZn1-xO晶体薄膜的结构和光学性能

在白宝石（sapphire）衬底上低温外延生长出了Mg_xZn_1-xO晶体薄膜.x射线衍射（XRD）及能量色散x射线（EDX）分析表明，Mg_xZn_1-xO薄膜的晶体结构依赖于薄膜中Mg的组分x，随着Mg组分的增大，Mg_xZn_1-xO薄膜的结构从与ZnO晶体一致的六方结构转变为与MgO晶体一致的立方结构.对Mg_xZn_1-xO薄膜的紫外透 关键词： 电子束蒸发反应 xZn_1-xO晶体薄膜')" href="#">Mg_xZn_1-xO晶体薄膜 结构和光学性能     

Structural and optical properties of Al1-xInxN epilayers on GaN template grown by metalorganic chemical vapor deposition

This paper reports that Al1 xInxN epilayers were grown on GaN template by metalorganic chemical vapor de-position with an In content of 7%-20%. X-ray diffraction results indicate that all these Al1 xInxN epilayers have a relatively low density of threading dislocations. Rutherford backscattering/channeling measurements provide the exact compositional information and show that a gradual variation in composition of the Al1 xInxN epilayer happens along the growth direction. The experimental results of optical reflection clearly show the bandgap energies of Al1 xInxN epilayers. A bowing parameter of 6.5 eV is obtained from the compositional dependence of the energy gap. The cathodoluminescence peak energy of the Al1 xInxN epilayer is much lower than its bandgap, indicating a relatively large Stokes shift in the Al1 xInxN sample.     

Synthesis and characterization of a new series of BiOI1−x−yBrxCly pigments

New bismuth oxyhalides of the type BiOI_1?xBr_x, form a complete solid solution series and crystallize in a layered tetragonal matlockite structure Color varies from yellow to red as x decreases from 0 75 to 0 and layer separation, c, increases from 8 45 to 9 16 Å The compounds have large intrinsic optical absorption coefficients (α > 10⁵ cm^-1). Used as pigments, they are light-fast but show less color saturation than PbCrO₄ of the same hue.     

高压下半磁半导体Cd1-xMnxSe的相变研究

利用金刚石对顶砧高压装置,并分别用光吸收和X射线衍射实验方法测量了Cd_1-xMn_xSe样品在高压下的相变,发现该样品的高压相变是不可逆,常压下Cd_1-xMn_xSe具有纤维锌矿结构,高压下变为NaCl结构,而卸压后成为闪锌矿结构,同时给出了Cd_1-xMn_xSe样品的相变压力及其与组分x的关系。 关键词：     

Optical properties of TlGaxIn1-xSe2-layered mixed crystals (0.5 ≤ x ≤ 1) by spectroscopic ellipsometry,transmission, and reflection measurements

The layered semiconducting TlGa_xIn_1-xSe₂-mixed crystals (0.5?≤?x?≤?1) were studied for the first time by spectroscopic ellipsometry measurements in the 1.2–6.2?eV spectral range at room temperature. The spectral dependence of the components of the complex dielectric function, refractive index, and extinction coefficient were revealed using an optical model. The interband transition energies in the studied samples were found from the analysis of the second-energy derivative spectra of the complex dielectric function. The effect of the isomorphic cation substitution (indium for gallium) on critical point energies in TlGa_xIn_1-xSe₂ crystals was established. Moreover, the absorption edge of TlGa_xIn_1-xSe₂ crystals have been studied through the transmission and reflection measurements in the wavelength range of 500–1100?nm. The analysis of absorption data revealed the presence of both optical indirect and direct transitions. It was found that the energy band gaps decrease with the increase of indium content in the studied crystals.