ZnS中Te等电子中心的时间分辨光谱研究

用时间分辨光谱研究了很大的Te组分范围内的ZnS1-xTex(x=0.005-0.85)合金的发光动力学特性,结果表明:不同形态的Te等电子中心具有不同的辐射复合寿命,从几个ns到几十个ns的范围内变化,当x=0.15左右时,寿命达到最大值(约40 ns).其物理机理源于不同的Te等电子中心具有不同的局域化特性.当Te组分较小时,等电子中心从Te1逐渐演变到Te2,Te3或Te4时,相应发光寿命增加,表现出不断增强的激子发光局域化特性;而当Te组分较大时,Te原子团变得较大,其局域势与基体原子势的相互作用增强,等电子中心的局域化特性减弱,而基体价带扩展态特征变得明显起来,相应发光寿命逐渐减小.还研究了激子束缚能随Te组分的变化以及发光强度随温度的变化关系,所得结果进一步支持了时间分辨光谱研究所得到的结论.

不同尺寸ZnS:Mn纳米粒子的静压光致发光研究

测量了ZnS:Mn纳米粒子以及相应体材料在不同压力下的光致发光谱.随压力增大,来源于Mn2+离子的4T1-6A1跃迁的桔黄色发光明显红移.体材料和10,4.5,3.5,3 nm的ZnS:Mn纳米粒子中Mn2+发光的压力系数分别是-29.4±0.3和-30.1±0.3,-33.3±0.6,-34.6±0.8,-39±1 meV/GPa,压力系数的绝对值随粒子尺寸减小而增大,该种尺寸关系由晶体场场强Dq和Racah参数B值的尺寸依赖性引起.1nm样品的Mn2+发光的特殊压力行为是因为样品的粒子尺寸比较小,另外,分布在Y型沸石中的纳米粒子的表面状况也不同于其它样品.

静压下ZnS∶Te中Te等电子陷阱的发光

研究了4块ZnS∶Te薄膜样品(Te组分从0.5%到3.1%)的光致发光谱在常压下的温度特性.对于Te组分较小的2块样品观察到2个发光峰,分别来自Te1和Te2等电子陷阱;而对Te组分较大的2块样品则只观察到1个来自Te2等电子陷阱的发光.我们还研究了这些发光峰在低温15K下的流体静压压力行为.观察到与Te1有关的发光峰压力系数比ZnS带边的要大很多,而与Te2有关的发光峰压力系数则比带边小.根据Koster-Slater模型,价带态密度半宽随压力的增加是Te1中心有较大压力系数的主要原因,而Te1和Te2中心的不同压力行为则是由于压力对两者缺陷势增强的不同效果引起的.

Surface Morphology and Photoluminescence of 1.3 μm Wavelength In(Ga)As/GaAs Quantum Dots

Self-organized In_(0.5)Ga_(0.5)As/GaAs quantum island structure emitting at 1. 35 (im at room temperature has been successfully fabricated by molecular beam epitaxy (MBE) via cycled (InAs)_1/( GaAs)_1 monolayer deposition method. Photoluminescence (PL) measurement shows that very narrow PL linewidth of 19.2 meV at 300 K has been reached for the first time, indicating effective suppression of inhomogeneous broadening of optical emission from the In_(0.5)Ga_(0.5)As islands structure. Our results provide important information for optimizing the epitaxial structures of 1.3 μm wavelength quantum dot (QD) devices.

气相和溶液多硫化物钝化InP表面的XPS和AFM研究

国家自然科学基金

稀土掺杂ZnS纳米晶中稀土离子与纳米基质之间的能量传递

以甲基丙烯酸为表面包覆剂在水/醇溶液中合成了ZnS:Eu~3+, ZnS:Tb~3+纳米晶，用傅里叶变换红外光谱和X射线粉末衍射谱表征了样品的表面与晶型，样品均为立方闪锌矿型，没有出现与稀土离子相关的相；用光致发光和激发谱研究了样品中的发光过程，其中ZnS:Tb~3+纳米晶中存在纳米基质与Tb~3+之间的能量传递，并引起Tb~3+的特征发射。

Al_xGa_(1-x)As/GaAs太阳电池MgF_2/ZnS双层减反射膜的研究

介绍了在AlGaAs/GaAs太阳电池上制备MgF_2/ZnS双层减反射膜的研究工作。引入了有效反射率R_e，并通过使R_e极小来实现减反射膜的优化设计，考虑了MgF_2/ZnS双层减反射膜与窗口层的耦合。实验上获得了良好的减反射膜，提高了AlGaAs/GaAs太阳电池的短路电流和效率，表明用R_e极小化来设计减反射膜是合理的。

静压下ZnS（0.02）Te（0.98）混晶的共振喇螺散射研究

于2010-11-23批量导入

Formation of ZnS clusters in xeolite-Y

于2010-11-23批量导入

Structural properties of polycrystalline silicon films formed by pulsed rapid thermal processing

A novel pulsed rapid thermal processing (PRTP) method has been used for realizing the solid-phase crystallization of amorphous silicon films prepared by PECVD. The microstructure and surface morphology of the crystallized films are investigated by X-ray diffraction (XRD) and atomic force microscopy (AFM). The results indicate that this PRTP is a suitable post-crystallization technique for fabricating large-area polycrystalline silicon films with good structural qualities such as large grain size, small lattice microstain and smooth surface morphology on low-cost substrate.

Surface morphology and optical property of 1.3 mu m In0.5Ga0.5As/GaAs self-organized quantum dots grown by MBE

Surface morphology and optical properties of 1.3 mum self-organized InGaAs/GaAs quantum dots structure grown by molecular beam epitaxy have been investigated by atomic force microscopy and photoluminescence measurements. It has been shown that the surface morphology evolution and emission wavelengths of InGaAs/GaAs QDs can be controlled effectively via cycled monolayer deposition methods due to the reduction of the surface strain. Our results provide important information for optimizing the epitaxial parameters for obtaining 1.3 mum long wavelength emission quantum dots structures. (C) 2002 Elsevier Science B.V. All rights reserved.

Photoluminescence of nanocrystalline SiC films prepared by rf magnetron sputtering

Amorphous Sic films are deposited on Si (111) substrates by rf magnetron sputtering and then annealed at 1200 degreesC for different times by a dc self-heating method in a vacuum annealing system. The crystallization of the amorphous Sic is determined by Raman scattering at room temperature and X-ray diffraction. The experimental result indicates that the Sic nanocrystals have formed in the films. The topography of the as-annealed films is characterized by atomic force microscopy. Measurements of photoluminescence of the as-annealed films show blue or violet light emission from the nanocrystalline Sic films and photoluminescence peak shifts to short wavelength side as the annealing time decreases.

Synthesis and luminescence of CdS/ZnS core/shell nanocrystals

CdS/ZnS core/shell nanocrystals were prepared from an aqueous/alcohol medium. A red shift of the absorption spectrum and an increase of the room temperature photoluminescence intensity accompanied shell growth.