ZnSe基底7～14μm波段宽带增透膜

简要叙述了7～14μm波段红外增透膜的膜料选择以及硒化锌基底上高性能红外增透膜的设计和工艺研究。介绍了离子辅助沉积技术沉积该膜的的工艺过程。给出了用该方法制备的7～14μm波段宽带减反射膜的实测光谱曲线,其峰值透过率高达98%以上,在设计波段范围内平均透过率大于97%,膜层附着性能好,光机性能稳定。这对于红外光学系统的应用具有十分重要的意义。     

Optical properties of Cl-doped ZnSe epilayers grown on GaAs substrates

We have determined the optical properties of a series of Cl-doped ZnSe epilayers grown on GaAs substrates using ellipsometry and prism coupling. Initially, the carrier concentrations were determined using Hall measurements for samples between 6.30×10¹⁶ cm⁻³ and 9.50×10¹⁸ cm⁻³. Using a variable angle spectroscopic ellipsometer in the energy range between 0.7 eV and 6.5 eV, we then obtained experimental spectra for each of the samples. By incorporating a three-layer model to simulate the experimental data, we determined the complex dielectric functions for these Cl-doped ZnSe epilayers. In order to facilitate this modeling procedure, we have complemented the ellipsometric results with prism coupling experiments that measured the film thickness and the index of refraction (at discrete wavelengths) very precisely. For the fundamental band gap, we observe a blue shift with respect to the doping concentration, which can be explained by the Burstein-Moss effect. In addition, we have determined the critical point parameters related to these specimens by fitting the second derivatives of both the real and the imaginary parts of the dielectric functions. Similar to several doped III-V semiconductors reported thus far, we find that in Cl-doped ZnSe epilayers, both E₁ and E₁ + Δ ₁ red shift, as well as a broadening with respect to the doping concentration.     

Synthesis and characterization of blue emitting ZnSe quantum dots

In this work we show a new experimental methodology to obtain ZnSe nanocrystals in aqueous solution aiming their application as biophotonic probes. The nanocrystals were obtained using a simple procedure based on the arrested precipitation of ZnSe in aqueous solution in the presence of a thiol-alkyl stabilizing agent, in air and at room temperature. Using post-preparative experimental procedures on the colloidal particles, blue and green emissions were observed. The structural characterization (powder X-ray diffraction and electronic transmission microscopy) shows that the particles were obtained in the quantum confinement regime (d=2-4 nm) and possess a zinc-blend crystalline structure. The optical properties of the suspensions were determined by electronic absorption, excitation and emission spectroscopies and are discussed in terms of their size and chemical compositions.     

以S、Se为原料的CVD ZnS、CVD ZnSe的化学反应分析

本文详细分析了用单质硫或单质硒为原料,在Zn-S-H2-Ar体系或Zn-Se-H2-Ar体系中化学气相沉积生长 ZnS和ZnSe晶体所发生的化学反应,认为在这两种化学气相沉积过程中所发生的化学反应是以锌蒸汽与硫或硒蒸汽反应来实现的.计算出了上述反应的△H、△S和△G这些热力学函数,并将该△G与采用H2S气体(Zn-H2S-Ar体系)和H2Se气体(Zn-H2Se-Ar体系)为原料的CVD ZnS和ZnSe做了对比.实验结果表明,以单质Se为原料生长的CVD ZnSe比以H2Se为原料的CVD ZnSe的努普硬度有显著的提高.     

Jahn－Teller变形后C60－的结构和电子光谱

用INDO系列方法对C₆₀^－进行几何构型优化,得到D_3d对称性的构型,表明C₆₀^－确实发生了Jahn-Teller畸变,导致单键变短,双键变长,形成10种键,6种不等同碳原子,并以此构型为基础,计算了C₆₀^－的电子光谱,与实验结果吻合;同时对光谱进行了理论指认;最后对C₆₀^－的3种构型：D_5d,D_3d,D_2h的几何构型、能量、光谱和反应特性进行了分析、比较和总结。     

Thermal conductivity of ZnSe by molecular dynamics simulation

Molecular dynamics simulation using the new fit of the empirical Tersoff Potential is applied to study the thermal properties of ZnSe at and below the room temperature. The resulting diffusivity and thermal conductivity are compared with the photoacoustic measurements on the grown ZnSe crystal. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

基于择优掺杂取向研究Y掺杂量对ZnTe电子结构和吸收光谱的影响

Zn Te由于其特有的禁带宽度,光学性质以及可重掺杂等特性,使得众多学者对其进行了系列的相关研究,但关于Y掺杂浓度和掺杂方式对Zn Te性质的影响却鲜有报道.作者采用密度泛函理论框架下的广义梯度近似方法,分别计算了Y在掺杂浓度为1.56at%、3.12at%、4.69at%下Zn Te的几何结构、能带结构、态密度分布、吸收光谱等性质,以及不同掺杂方式对体系的影响.结果表明:在掺杂浓度为3.12at%,掺杂方式不相同时,掺杂原子沿[111]晶向排布的形成能最低,即[111]晶向为择优晶向.当掺杂浓度为4.69at%时,择优晶面为(111)面.若要实现更高浓度的Y掺杂,沿(111)晶面掺杂更容易实现.对于实验而言,更高浓度的Y掺杂,掺杂原子在Zn Te体系中更容易沿(111)晶面进行集中排列. Y掺杂Zn Te后,体系的禁带宽度变大,吸收光谱发生蓝移,对可见光的吸收强度减小.在浓度为3.12at%时禁带宽度最大,蓝移现象最明显,吸收强度最小. Y掺杂后体系变为n型半导体,可以使用这种掺杂方式制作P-N结二极管．     

In-situ ellipsometric measurements of the MBE growth of CdTe/HgTe and CdTe/ZnTe superlattices

Phase modulated ellipsometric data recorded during molecular beam epitaxial growth of CdTe/HgTe and CdTe/ZnTe superlattices on (100) and (211)B oriented Cd_0.96Zn_0.04Te and GaAs substrates are presented. The measurements provide a continuous monitor of the growth process, thickness, growth rate, compositional data, and evidence of interdiffusion in CdTe/HgTe superlattices at elevated temperatures. The thickness measurements are independent of growth kinetics and surface orientation and agree well with those obtained from x-ray diffraction and reflection high energy electron diffraction. Ellipsometry shows that the incorporation of Hg in CdTe is significantly higher on (100) oriented surfaces than on (211)B oriented surfaces. Fine structure in the data from CdTe/ZnTe superlattices may be associated with a surface reconstruction during deposition of each CdTe layer. The experimental results for CdTe/HgTe superlattices compare well with results of thin film multi-layer calculations. The general applicability of ellipsometry as an in-situ analytical technique for epitaxial growth of a range of semiconductor superlattices is discussed.     

A continuously variable attenuator for the CO2 laser

A continuously variable attenuator for the CO₂ laser, causing minimal degradation of beam quality, is implemented using rotating ZnSe wedges, and is capable of transmissivities between 0.3% and 18%, and between 27% and 89%. The transmissivity at any particular setting was measured to be essentially constant for wavelengths from 9.27 μm (9R20) to 10.77 μm (10P36).     

Integrated heterostructure devices based on II–VI compound semiconductors

Integrated heterostructure devices which combine small band gap and large band gap II–VI materials in multilayered structures for light emission and detection applications are described.