Temperature dependent photoluminescence studies of ZnSe:I single crystals grown by chemical vapor transport

The single crystal ZnSe:I sample was grown by the chemical vapor transport (CVT) method using iodine as the transporting agent. The iodine incorporates itself effectively as a donor in the lattice. The sample shows a 〈111〉 optical quality surface and has an absorption edge at 2.55 eV due to a deep impurity band nearly 0.15eV below the conduction band. The photoluminescence emission spectra of this crystal have been measured for its temperature dependence as well as for excitation energy dependence. The photoluminescence is in accordance with a donor-acceptor complex formation involving iodine activated donors and self-activated acceptors. The configuration coordinate model has been used to explain the temperature dependent changes in the peak position and the bandwidth of the emission band. The decrease in luminescence efficiency with increasing temperature is explained by using a simple model for thermal quenching. The activation energy at low temperature range (T<200K) is different from that at high temperature range (200K<T<300K).     

基于ZnSe/Ag/ZnSe可见区透明导电薄膜

利用红外光学材料ZnSe和金属Ag在室温下采用电子束蒸发镀膜技术研制了透明导电薄膜ZnSe/Ag/ZnSe,该薄膜的电子浓度为1.208×1020 cm－3,电子迁移率和电阻率分别为17.22 cm2 V－1 s－1和2.867×10－5 Ω·cm,功函数达到5.13 eV,在可见区的平均透过率理论模拟值超过80%,而测量结果为63.8%,测量的最高透过率为83%.结果表明,该透明导电薄膜具有良好的光学和电学性能,可作为透明电极应用于发光二极管等光电子器件中.     

Chemischer Transport fester Lösungen. 27. Mischphasenbildung und chemischer Transport im System ZnSe/GaAs

Chemical Vapor Transport of Solid Solutions. 27. Formation of Solid Solutions and Chemical Vapor Transport in the System GaAs/ZnSe The miscibility of ZnSe and GaAs as a function of temperature has been investigated. At temperatures above 1100 °C GaAs and ZnSe form out a continous crystalline solid solution. The phase diagram of this system is presented. Mixed crystals in the system GaAs/ZnSe can be prepared by means of chemical vapor transport using iodine as transport agent. Mass spectrometric investigations have shown the formation of AsSeI(g), an up to now unknown triatomic molecule. First approximate thermodynamic Data for AsSeI(g) are given. The knowledge of AsSeI and its thermodynamic stability is necessary to understand the transport phenomena.     

Ultrasensitive and Selective Detection of Cd(II) Using ZnSe‐Xanthan Gum Complex/CNT Modified Electrodes

This work describes for the first time the employment of water soluble GSH‐ZnSe QDs stabilized by XG and MWCNT for electrode modification in the detection of Cd ions in a highly sensitive and selective manner resulting from the unique structure and surface chemistry of the used QDs. The surface of a glassy carbon (GC) electrode was modified through casting a thin layer of multiwalled carbon nanotubes (MWCNT) followed by a complex layer of ZnSe quantum dots (QDs) stabilized by xanthan gum (XG). Due to the electrocatalytic properties of MWCNT and electroanalytical performance of ZnSe‐XG complex, the new modified electrode significantly improves the sensitivity and selectivity of Cd(II) detection and exhibits enhanced performance in comparison to bare GC, ZnSe/GC and ZnSe/MWCNT/GC electrodes. Strong interactions between ZnSe QDs and XG resulting from hydrogen bonding and complexing association led to stabilization of ZnSe QDs and higher affinity towards Cd(II) ions adsorption compared to a ZnSe QDs film alone. The modified electrode showed linear response in a wide concentration range from 100 nM to 5 μM (R²=0.9967) along with a high sensitivity of 156.6 nA ⋅ mol⁻¹ ⋅ L⁻¹ and a low detection limit of 20 nM. The electrode shows high selectivity to Cd with negligible interference from other metal ions and salts.     

电场调制下单量子阱ZnCdSe／ZnSe的激射行为研究

近年来,随着宽禁带Ⅱ－Ⅵ族半导体激光器取得突破性进展［１］,对ＺｎＳｅ基超晶格与量子阱的受激发射也进行了广泛的研究［２,３］,同时对电场调制下的ＺｎＳｅ基超晶格的受激发射也有过报导［４］．但对于电场调制下的ＺｎＣｄＳｅ／ＺｎＳｅ基单量子阱的激射行为研...     

CVD法生长ZnSe的工艺分析

采用单质Se为原料(Zn-Se-H2-Ar体系)来生长CVD ZnSe,初步分析了这种工艺的机理,并详细分析了各种工艺参数对生长ZnSe的影响.这些工艺参数包括沉积腔的温度和压力,Zn坩埚和Se坩埚的温度,各路载流气体的流量.对这些工艺参数进行调整和精确控制,并控制好Zn蒸气和Se蒸气气嘴处的ZnSe生长形态,生长出了质量良好的ZnSe多晶体,透过率超过70;.     

Raman spectra of ZnSe nanoparticles synthesized by thermal evaporation method

ZnSe nanoparticles were synthesized by using a thermal evaporation method for a vapour phase reaction of zinc and selenium sources. The sample was characterized by XRD, TEM, HRTEM and Raman spectroscopy. Raman spectra of longitudinal-optical (LO) like mode was analysed by a macroscopic continuum dielectric model. Large broadening of LO-mode is homogeneous and comes from the relaxation of the phonons at the interface and contribution of defects. Surface modes give the main contribution to the asymmetry of the lineshape.     

分子束外延ZnSe/GaAs材料的拉曼散射研究

用分子束外延(MBE)技术，在GaAa(100)衬底上生长了厚度从0．045μm到1．4μm的ZnSe薄膜。通过室温拉曼光谱的测量对ZnSe薄膜纵光学声子(Longitudinal-opticalphonon)的谱形进行了分析。用拉曼散射的空间相关模型定量分析了一级拉曼散射的型间相关长度与晶体质量之间的关系，结果表明ZnSe外延层的晶体质量随着外延层厚度的减薄是渐渐退化的，这是由于界面失配位错引入外延层所致，理论分析与实验结果相吻合。     

高压下ZnSe 纳米带的结构相变及拉曼散射研究

 利用高压原位角散X射线衍射实验研究了ZnSe纳米带的结构稳定性。发现样品在12.6 GPa 附近存在一个从立方闪锌矿型到立方岩盐矿型的结构相变,并且在相变点附近存在较大的体积收缩,相对体积变化率达13%。利用Birch-Murnaghan 状态方程拟合,得到了闪锌矿相的体弹模量约为56 GPa,略低于体材料的体弹模量（约67 GPa）;并得到其立方岩盐矿相的体弹模量约为116 GPa。高压拉曼散射实验结果表明,横光学声子模散射峰在5.5 GPa压力附近发生劈裂,纵光学声子模散射峰在12.8 GPa压力以上逐渐消失。根据角散实验的体弹模量数据,计算得到了闪锌矿相中对应不同声子模式的格林爱森常数。     

单源真空蒸发法制备ZnSe薄膜的实验研究

本文采用单源真空蒸发法制备了ZnSe薄膜,利用电子探针、X射线粉晶衍射等现代测试手段研究了蒸发温度(700～1050 ℃)、基片温度(0～200 ℃)、基片材料(单晶硅、玻璃)以及热处理温度(300～400 ℃)等因素的改变对ZnSe薄膜的成份和结构的影响规律,建立了单源真空蒸发沉积ZnSe薄膜及热处理的实验方法.