Time-resolved PL Spectra Study of Ordered Ga_(0.52)In_(0.48)P Alloys

【中文摘要】 在室温和低温液氮下 ,研究了有序和无序 Ga0 .52 In0 .4 8P的时间分辨发光谱。对实验结果的拟合表明 ,有序 Ga0 .52 In0 .4 8P的发光呈双指数规律衰退。其中快过程对应着有序区域上载流子的复合 ,慢过程则对应着有序区域和无序区域的空间分离中心上载流子的复合。无序 Ga0 .52 In0 .4 8P的发光在室温下呈单指数规律衰退。同时从低温下的时间分辨发光谱还可以看出有序样品的发光峰随着延迟时间的变长而蓝移 ,说明低温下在有序 Ga0 .52In0 .4 8P中存在着载流子从无序区域到有序区域的转移 【英文摘要】 The time resolved photoluminescence(TRPL) spectra of ordered and disordered Ga 0.52 In 0.48 P alloys grown by MOVPE were investigated.The least square fitting of the luminescence decay spectra of ordered alloys shows that there exist two exponential processes:The short lifetime process was corresponding to the high energy peak in PL spectra which is attributed to the recombination of the carriers in the ordered domains and the long lifetime process was corresponding to the low energy peak in the P...国家自然科学基金 (编号:69776011); 福建省自然科学基金 (编号:A9910004和 A0110007

Influence of coal characteristics on laser-induced plasmas

peer reviewedEight kinds of typical coal samples were chosen for studying the influence of coal characteristics on laser—induced plasmas．Element analysis and industry analysis were carried out for every sample．Experimental study on the interaction between laser and different coal samples was completed，and factors affecting laser plasma were analyzed，such as coal moisture and coal dust．The experiment result indicates that the coal samples with different coalification degrees have different plasma time—resolved spectral characteristics，all of them tend to rise at the beginning of plasma formation (< 1us)，then with the decay of plasmas emission．they tend to decrease in about 1us，while secondary ionization occurs in highly coalificated coals after 2 us．The plasma temperature differs from one kind to another，the higher the coalification degree is，the higher the plasma temperature will be

Photoluminescence of Multilayer InAs Quantum Dots

采用MBE设备生长了多层InAs/GaAs量子点结构,测量了其变温光致发光谱和时间分辨光致发光谱。结果表明多层量子点结构有利于减小发光峰的半高宽,并且可以提高发光峰半高宽和发光寿命的温度稳定性。实验发现,加InGaAs盖层后,量子点发光峰的半高宽进一步减小,最小达到23.6 meV,并且发光峰出现红移。原因可能在于InGaAs盖层减小了InAs岛所受的应力,阻止了In组分的偏析,提高了InAs量子点尺寸分布的均匀性和质量,导致载流子在不同量子点中的迁移效应减弱。Multilayer InAs/GaAs quantum dots structures were grown by molecular-beam epitaxy(MBE).The steady-state and time-resolved photoluminescence of the samples were measured at various temperatures.Results showed that multilayer structures could not only narrow the photoluminescence FWHM(full width at the half maximum) but enhance the stability of the photoluminescence lifetime and FWHM.As for the quantum dots with InGaAs cap layer,the photoluminescent spectra became narrower(the narrowest FWHM was only 23.6meV) and the photoluminescent wavelength became longer.The possible reason for the above phenomena was that the InGaAs cap layer could both release the strains in InAs islands and inhibit segregation of In components,resulting in the weaker migration among different quantum dots

时间分辨光谱电化学进展

电极 /电解质的界面动力学是当代电化学基础研究的核心领域及主要的发展方向之一 .该方面研究希望能够从分子水平上对电极反应的基元步骤进行直接观察与分析 .对时间分辨光谱电化学中的红外、Raman、紫外可见等光谱技术的循呼发展现状进行了系统的介绍 ,各种光谱技术所能达到的时间分辨水平分别为 :红外 (几微秒 ) ,Raman(几十毫秒 ) ,紫外可见 (几微秒 ) .并着重介绍了本室建立的时间分辨水平为微秒数量级的紫外可见光谱测量系统的原理和应

Photoluminescence Characteristics of InAs Self-assembled Quantum Dots in InGaAs/GaAs Quantum Well

在InGaAs/GaAs量子阱中生长了两组InAs量子点样品,用扫描电子显微镜(SEM)测量发现,量子点呈棱状结构,而不是通常的金字塔结构,这是由多层结构的应力传递及InGaAs应变层的各向异性引起的。采用变温光致发光谱(TDPL)和时间分辨谱(TRPL)研究了其光致发光稳态和瞬态特性。研究发现,InGaAs量子阱层可以有效地缓冲InAs量子点中的应变,提高量子点的生长质量,可以在室温下探测到较强的发光峰。在量子阱中生长量子点可以获得室温下1 318 nm的发光,并且使其PL谱的半高宽减小到25 meV。Two types of InAs quantum dots grown in InGaAs/GaAs quantum well(DWELL) were fully investigated by time-resolved(TR) and temperature dependent photoluminescence(TDPL).Scanning electron microscopy(SEM) measurements show that the shape of quantum dots is prismatic,but not the common pyramid shape.We consider that it is attributed to stress transition of multi-layer structure and anisotropy of InGaAs strained layer.DWELL structures could combine both the effects of InGaAs buffer layer and cap layer and even effectively release the stress between the buffer layer and the QDs, which may greatly improve the QDs quality.Strong PL signal emitting at 1 318 nm can be detected at room temperature and the full width at half maximum of PL spectrum is only 25 meV at some temperature.浙江省舟山市科技项目(06110);; 浙江海洋学院人才引进项目(211050041

电化学调制时间分辨紫外可见光谱技术及其在电显色研究中的应用

七十年代发展起来的电化学现场(in situ)谱学技术将电化学学科的研究推向分子水平。随着研究深入到分子动态过程,时间分辨谱学技术愈显得重要。紫外可见光谱是检测含π电子、非键电子(如N,O,S,卤素原子)基因、无机配合物分子和电荷转移复合物分子的重要手段。包含这些基团的体系在电化学和生命科学中广泛存在,认识其动态行为意义重大。但目前快速扫描法测量一条紫外可见光谱,最快只能达5ms。近年来,发展起了一种新型光谱探测仪器——光多道分析仪(Optical Multichannel Analyzer,OMA)。其核心由自扫描光敏二极管列阵或光导摄象管构成,能够对多个检测通道(象元)同时完成光电转换。它具有测量速度快、灵敏度高的优势

The study of optical properties on InAs self-organized quantum dots

由于半导体量子点具有零维电子特性，它不仅成为基本物理研究的重要对象，也成为研制新一代量子器件的基础。正因如此，量子点材料及器件成为目前国际上最前沿的研究课题之一。GaAs基InAs自组织量子点因其成本低廉、器件工艺成熟，成为替代InP基材料、制备光纤通信用1.3－1.55&micro;m发光激光器的热门材料之一。本文采用分子束外延技术制备了高质量的GaAs基InAs自组织量子点材料。利用原子力显微镜（AFM）、扫描电子显微镜（SEM）、变温及时间分辨的光致发光谱（PL）等手段，分别研究了InGaAs应变层（指在InGaAs层上生长量子点，下同）、InGaAs盖层、InGaAs/InAlAs联合...Quantum dots (QDs), with zero-dimensional electronic properties, have stimulated great interest due to their important roles in fundamental physical research and for developing novel devices. In recent years, it has been one of frontier topics of materials science to study the characterization of self-organized quantum dots and device applications. GaAs-based In(Ga)As self-organized QDs have becom...学位：理学博士院系专业：物理与机电工程学院物理学系_凝聚态物理学号：B20022400

Studies of Luminescent Properties for InGaAsN Quantum Wells

针对InGaAsP/InP1.3-1.55μm长波长激光器具有温度特性差的缺点，近年来提出了InGaAsN/GaAs新型结构材料。它可以用于制造高性能的长波长垂直腔面发射激光器(VCSEL)。因此，近年来InGaAsN材料成为长波长光电器件的一个重要研究课题。 本文通过高分辨率X-射线衍射(HRXRD)实验与拟合得到In的组分和量子阱的阱宽。结合理论计算对光致发光(PL)谱中InGaAs和InGaAsN量子阱的11H发光峰进行指认，并拟合得到样品中N的组分，理论与实验结果吻合得相当好。比较样品的变温PL谱发现，在InGaAs中掺入少量的N可以使发光波长明显红移，而且适当提高N的组分有利于提高...InGaAsP/InP long-wavelength semiconductor lasers in 1.3-1.55μm wavelength has a disadvantage of relatively poor temperature characteristics. Recently, InGaAsN/GaAs system is proposed to solve the problem as a long wavelength material. Most attractive is the realization of long wavelength vertical cavity surface emitting laser (VCSEL) with high performance using InGaAsN/GaAs. Therefore, InGaAsN mat...学位：理学硕士院系专业：物理与机电工程学院物理学系_凝聚态物理学号：20012403

不断创新的电化学研究方法（厦门大学电化学研究工作简介之二）

不断创新的电化学研究方法（厦门大学电化学研究工作简介之二）林仲华，罗瑾，田中群，孙世刚，林昌健，毛秉伟，杨勇，林华水执笔（固体表面物理化学国家重点实验室，厦门大学化学系，厦门３６１００５）１历史的回顾与自然科学的其它分支学科一样，电化学科学的建立和纵..

自组织生长InAs量子点的发光性质研究

通过对加InGaAs自组织生长量子点的变温光致发光谱以及时间分辨谱的研究，发现低温下量子点的发光强度和光生载流子的寿命不变；中间温度区载流子寿命随温度升高而变大；更高温度时，发光强度和载流子寿命均随温度升高而快速下降