固态器件和材料研究的新进展：1993年国际固态器件和材料会议介绍

固态器件和材料研究的新进展──１９９３年国际固态器件和材料会议介绍王迅（复旦大学应用表面物理国家重点实验室，上海２００４３３）一、概况１９９３年国际固态器件和材料会议于８月２９日至９月１日在日本干叶举行。会议主要议题有：（１）硅分子束外延（第五届国际...     

功率型发光二极管的研究与应用进展

文章首先对功率型发光二极管的起源和发展作了回顾和简要的叙述．然后以固体光源照明为目标，给出了几种可见光功率发光二极管芯片和封装的典型结构，并且对它们各自的特点进行了比较．最后指出了功率发光二极管作为固体光源取代真空灯泡用于照明在未来的五至十年内将成为现实．     

基于金属卤化物钙钛矿材料的高效发光二极管

金属卤化物钙钛矿半导体既在光伏器件研究中获得巨大进展,又在发光应用中体现出明显优势。金属卤化物钙钛矿半导体的荧光转化效率高、发光峰形窄、发射光谱可调控并可覆盖整个可见光范围,从而使得该类材料所制备的发光二极管有望满足下一代显示技术应用的性能要求。文章在简要叙述发光二极管基本原理的基础上,分别介绍了钙钛矿材料的结构和荧光特性、钙钛矿发光二极管的电致发光特性,以及钙钛矿发光二极管进入实际应用所必须解决的器件寿命、离子迁移和光谱不稳定性等主要技术问题,最后讨论了钙钛矿发光技术所面临的机遇和挑战。     

一种新的半导体材料和器件结构:COS

国际半导体技术发展进程表预期器件的特征尺寸不久将减小到0.1μm以下，SiO2作为MOS器件栅介质遇到不可克服的困难，人们在寻找新的栅介质材料时，提出一种新的结构，称为半导体上的晶态氧化物（COS），最近，COS被用作Si衬底上生长GaAs的过渡层，成为半导体材料和器件发展中一项新的突破，文章对这一结构的进展情况做一简要介绍。     

用于投影机的发光二极管照明单元

目前的投影机光源——高压汞灯存在寿命短、色温高、存在有害光线、发热集中等缺点,严重制约了投影机进入家庭应用领域。发光二极管的最近发展为其作为高压汞灯的替代光源提供了可能性。提出了一种由一个发光二极管、一个准直镜、一个前蝇眼透镜和一个后蝇眼透镜组成的用于投影机的发光二极管照明单元,由数个照明单元加上会聚透镜则构成一个基本的照明系统。发光二极管的发光经准直镜压缩光束发散角后被前蝇眼透镜分割为多个细光束,会聚透镜将每个细光束都叠加会聚到显示芯片上,实现光能量的会聚和光场再分布．以满足投影机对光通量和光场均匀性等方面的要求,后蝇眼透镜用于与后续光路的匹配。作为照明单元的一个应用实例,文中分析了一种单片式硅上液晶投影机。     

半导体材料科学发展的历史回顾

半导体科学技术是２０世纪中最伟大和最重要的科技成就之一。在高新技术迅速发展的今天，重温其发展历程，总结其发展规律和认识其发展特点，具有重要的现实意义。作者着重评述了近半个世纪以来，半导体科学技术在材料、物理、器件与工艺四个领域内所取得的一系列重大进展。     

面向器件化的激光照明用荧光材料设计——简评与展望

激光照明用荧光材料已成为固态照明领域的研究热点。随着相关研究的不断深入和细化,科研人员对于荧光材料的认知也在不断提升。然而,现有激光照明用荧光材料的设计和研究思路在很大程度上仍受到wLED产业的影响,在材料器件化的过程中会存在种种问题。本文旨在从工程应用角度出发,探讨激光照明用荧光材料应具备的核心特性。首先简述荧光材料应用于激光照明和大功率wLED场景下的区别;其次指出一些现有荧光材料设计和表征中存在的误区;再次归纳荧光材料在面向激光照明应用时的设计规则及其机理;然后,介绍一些商用荧光材料的设计和封装方案,并探讨几种潜力较好的材料设计和制备方案;最后,展望相关研究的发展趋势。     

有机激光材料及器件的研究现状与展望

有机激光器因其制备简单, 价格低廉和易于集成等优势, 一直以来备受科研工作者的关注. 与无机激光介质相比, 有机激光材料来源广泛, 并具有发射光谱宽, 吸收与发射截面积大等特性, 因而有很大的发展潜力. 本文从激光的基本原理出发, 对有机激光材料的种类、特性进行了归纳, 并总结了高效有机激光材料的普遍特征; 分类讨论了常见有机激光微腔的类型与特点, 对有机激光系统内增益与损耗之间的动态关系进行了探讨. 鉴于实现电抽运激光一直以来都是有机激光领域期待解决的难题, 本文重点讨论了当前电抽运有机激光的研究现状和发展瓶颈, 以及科研工作者们对此问题的不懈探索和已有的工作基础. 最后总结了光抽运有机激光近年来的总体进展, 未来的研究方向, 这对于读者拓展新的研究思路有很好的参考和借鉴意义.     

第十七届全国化合物半导体材料、微波器件和光电器件学术会议(第二轮通知)

由中国电子学会半导体与集成技术分会、电子材料分会主办,河南大学承办的第十七届全国化合物半导体材料、微波器件和光电器件学术会议将于2012年10月13日至15日在历史文化名城河南省开封市召开。会议将邀请国内外知名学者就化合物半导体材料、微波器件和光电器件等有关学术领域的前沿热点问题进行交流、总结和展望。我们由衷地欢迎国内外广大学者和科研人员踊跃投稿并参加会     

固态照明光源的基石--氮化镓基白光发光二极管

首先回顾了照明光源的简单历史 ,然后介绍了发光二极管 (LED)发展到大功率白光LED的历史 ,接着简述了国内外发展现状 ,主要技术路线及其特点 .最后阐述了作者在这方面的研究工作进展状况 ,对其发展趋势提出了一些看法 .     

Modified wide radiating lenses of the power-chip light emitting diodes for a direct-lit backlight

Modified wide radiating lenses of the power-chip light emitting diodes (LEDs) for a direct-lit backlight unit of a liquid crystal display (LCD) are numerically investigated. To improve the optical properties of the backlight, the lens of the Golden DRAGON^® ARGUS^® LED, the cluster of LEDs, and the cluster arrangement for the 32-in bottom-lit backlight unit of a LCD are modified and verified by optical tracing simulation software. First, the central section shape is modified and analyzed to reduce the angular luminous intensity in the small angle range. The results show that the modifying lens method can effectively realize the aim. Then, several LEDs with the modified lenses are put in 32-in backlight. It is shown that the uniformity and efficiency of the new backlight are obviously better than the ones of the original type.     

发光二极管测试技术和标准

文章从发光二极管的空间能量分布和光谱能量分布两个方面叙述了光和辐射参数测试的原理和方法．讨论了辐射通量和光通量的基本概念、测量方法及相互之间的关系．在实际应用中，发光二极管的发光强度和辐射功率及他们的空间分布是常需要测量的参数．文章从基于人类视觉特性的色度学原理出发，讨论了发光二极管的光谱能量分布和重要的色度学参数以及相应的测试标准问题．     

基于发光二极管和导光板的彩色光源色度的测量

介绍一种由三色发光二极管和导光板组成的适合物理实验色度测量教学的彩色面光源,并给出了测量该光源色度的实验方法．     

High-efficiency silicon light emitting diodes

Silicon has been regarded as a notoriously poor emitter of light fundamentally due to its indirect bandgap. However, as an elemental rather than a compound semiconductor, it has the advantage of fewer background defects as well as well-developed approaches to interface passivation. By minimising parasitic optical absorption and non-radiative bulk and surface recombination, and by enhancing the effective optical photon generation volume, respectable silicon light emission efficiencies are demonstrated. These are within the range of direct gap III–V semiconductors and higher than any at low powered densities. Possible applications are also discussed.     

Effects of reflector-induced interferences on light extraction of InGaN/GaN vertical light emitting diodes

We provide a large F-P cavity model to analyze the effects of reflector-induced interferences on light extraction of InGaN/GaN vertical light emitting diodes (VLEDs). It shows that the distance (d) between the active region and the metal reflector has a significant influence on extraction efficiency due to interferences. The maximum in extraction efficiency corresponding to the optimal d is about three times the neighboring minimum. The reflector of different metals is considered in this model and the results show that the optimal d and the value of the maximum in the extraction efficiency are directly related to the type of metal, which can be attributed to varied reflection phase shift and reflectivity on different metals, respectively.     

中国半导体照明发展综述

半导体照明是21世纪初兴起的产业,也是我国第三代半导体材料成功产业化的第一个突破口,技术发展日新月异,是国际高科技领域竞争的焦点之一。目前,我国半导体照明产业已经形成了完整的产业链,功率白光LED、硅基LED和全光谱LED等核心技术同步国际,紫外LED、可见光通讯、农业光照和光医疗等创新应用走在世界前列。介绍了我国在半导体照明方面的研究进展,回顾了相关产业的发展情况,并对未来进行了展望。     

Measurement of the thermal characteristics of packaged double-heterostructure light emitting diodes for space applications using spontaneous optical spectrum properties

In this paper, the thermal characteristics of packaged infrared double-heterostructure light emitting diode (DH-LED), used in space applications, are measured under conditions that reproduce space environments. The characterisation uses spontaneous optical spectrum characteristics, current–voltage curves and optical power measured under a primary vacuum (<10⁻² Torr) at temperatures between −30 and 100 °C. The investigations have been specifically oriented toward the extraction of junction temperature in the steady-state regime and junction-to-case thermal resistance. A specific model based on semiconductor theory for electrical transport has been used to calculate the shape of the spontaneous emission spectrum between the band-gap energy and higher energies and its change versus temperature. A linear relation between the junction temperature and the dissipated power has been found for various case temperatures appropriately controlled in a LN₂ cryostat. These results confirm that thermal behavior of DH-LEDs depends on both environment temperature and dissipated power level in the active zone and that the junction-to-case thermal resistance is not constant over a large range of temperatures, diminishing at higher currents as already reported by recent papers on high brightness DH-LED. Finally, this study could represent a practical non-destructive method providing qualitative information about variations of junction temperature and junction-to-case thermal resistance taking into account an industrial qualification framework approach based on electroluminescence analysis, frequently measured by manufacturers or end-users.     

Enhancement of the light extraction of GaN-based green light emitting diodes via nanohybrid structures

Improvement in the light extraction efficiency (LEE) of GaN-based green light emitting diodes (LEDs) with ZnO nanostructures synthesized by a hydrothermal method is reported. Formation of ZnO nanorods, hemispheres, and cones was controlled by varying the pH of the aqueous synthesis solution. The shape of the ZnO nanostructures integrated onto the LEDs shows a strong relationship with the LEE characteristics of GaN-based green LEDs. The electroluminescence (EL) intensity of LEDs covered by ZnO nanostructures increased compared to conventional LEDs. In terms of LEE, LEDs with surface-textured ZnO hemispheres showed the highest EL intensity, which can be attributed to an increase in the effective critical angle, the escape cone, and multiple scattering. Finite difference time domain (FDTD) simulation was conducted to theoretically confirm the experimental results.