GaN基光电子材料及器件的研究

GaN材料是性能优越的化合物半导体,与其相关的合金材料可以制作出高亮度蓝光、绿光发光二极管、紫外探测器、半导体蓝色激光器(LD)等具有重要应用价值的光电子器件,因而备受重视,本文综述了GaN基光电子器件研究开发现状及其应用前景。     

GaN基和GaAs基半导体激光器的电学特性研究

介绍了一种能够全面表征半导体二极管器件的电学特性的方法,此方法结合半导体二极管的正向交流特性和直流特性,称之为正向交流小信号法。利用该方法深入地研究和对比分析了GaN基和GaAs基半导体激光器的电学特性,包括表观电容、串联电阻和理想因子。实验结果表明,对于GaN基和GaAs基半导体激光器,其开始发光的过程同步于其电容由正转变为负的过程。进一步实验结果表明,GaN基半导体激光器比GaAs基半导体激光器具有更大的串联电阻和更大的理想因子。这是由于GaN基激光器的器件工艺不够完善以及外延生长的GaN材料具有很大的位错密度。该研究为提高和改善GaN基激光器的性能提供了必要的依据以及理论指导。     

GaN基材料半导体激光器综述

叙述了激光器材料的发展,回顾了GaN薄膜制备的几个技术进展,总结了GaN基材料激光器(LDs)的发展历程。     

北大成功研制出氮化镓基激光二极管

北京大学物理学院宽禁带半导体研究中心研制的氮化镓基激光二极管实现了电注入激射，激光波长405nm，峰宽0．12nm。这是继2004年7月该中心率先在国内获得光泵浦GaN基激光器受激发射之后所取得的又一突破。GaN基激光器是波长最短的半导体激光器．波长为405nm范围的蓝一紫光GaN基激光器是发展下一代大容量高密度光存储信息技术的关键性器件。在国防建设、生物、环境、照明、显示、打印和医疗等领域，也具有广阔的应用前景和巨大的市场需求。研制GaN基激光器是国家高科技攻关的重要项目之一。     

采用硼化合物的蓝绿光半导体激光器

目前世界范围都在积极研究发射蓝绿光的半导体激光器制作。短波长激光的高效产生引发了众多引人注目的应用，如光数据存储、印刷技术、彩色显示技术、医学、以至分析和传感。以往短波激光二极管都是以Ⅱ-Ⅵ族半导体ZnSe和Ⅲ-Ⅴ族半导体GaN基材料制成。现在维尔茨堡大学则用新材料制成绿光激光器。该校多年来一直在研究Ⅱ-Ⅵ族半导体的制作和物理特性。除基础研究外，对ZnSe激光器的应用研究越来越引起重视。在此领域，该校一方面制作和优化传统材料ZnMgSSe绿光激光器。在W．Faschinger教授的带领下，取得了举世瞩目的成就。重点是在分…     

金刚石的制作及其光电应用

许多在紫外和可见光波长发光的器件使用Ⅱ-Ⅵ和Ⅲ-Ⅴ族二元材料。介电材料的带隙越大，发射光的波长就越短。数据存储需要更短的波长，但很难找到合适的材料。因此，蓝光激光器面临的困难要远大于红光和绿光激光器，直到日本学者开发了一种基于GaN的室温蓝光激光器，发射光的波长在450 nm以下。Nichia现已批量生产蓝光激光器，世界很多研究组都在开发极具商业前景的GaN蓝光发射器和光子探测器。要获得更短波长，钻石值得考虑，因为它具有大带隙（约5.5eV)。但对于金刚石电子元件就不同，因为以化学气相淀积制造单晶金刚石很困难，而这对…     

GaN基紫外探测器

随着GaN基紫外材料的日益成熟,GaN基紫外探测器发展迅速,被认为是和发光二极管、激光器同样重要的器件。本文讨论了紫外探测的意义,介绍了国内外近期研制的各种器件结构的GaN基紫外探测器和紫外焦平面。     

GaN基半导体材料研究进展

简单回顾半导体短波长激光器的发展过程，总结了GaN基激光二极管的发展以及GaN薄膜的几点技术进展。     

热超声倒装焊在制作大功率GaN基LED中的应用

设计了适合于倒装的大功率GaN基LED芯片结构,在倒装基板硅片上制作了金凸点,采用热超声倒装焊接(FCB)技术将芯片倒装在基板上.测试结果表明获得的大面积金凸点连接的剪切力最高达53.93 g/bump,焊接后的GaN基绿光LED在350 mA工作电流下正向电压为3.0 V.将热超声倒装焊接技术用于制作大功率GaN基LED器件,能起到良好的机械互连和电气互连.     

GaN基激光器光增益和内部光损耗的测量

采用变条长方法实验测量了GaN基短波长激光器样品的放大自发发射谱,确定了样品的光增益和光损失系数,并发现了样品中存在着严重的光增益饱和的现象。证实了变条长方法对于研究GaN基短波长激光器性能的可行性。进一步比较了两种不同结构的激光器样品在增益和增益饱和方面的性能差别,同时指出样品外延时生成的裂纹,可能是造成这一差别的原因。     

100-mW kink-free blue-violet laser diodes with low aspect ratio

400-nm-band GaN-based laser diodes (LDs) operating with a kink-free output power of over 100 mW and having a low aspect ratio of 2.3 have been successfully fabricated for the first time. A new ridge structure, in which the outside of the ridge is covered with a stacked layer of Si on SiO/sub 2/ and the ridge width is as narrow as 1.5 /spl mu/m, is applied to realize high kink-free output power with a wide beam divergence angle parallel to the junction plane. A new layer structure around the active layer is demonstrated to be quite effective for obtaining a narrow beam divergence angle perpendicular to the junction plane, maintaining low threshold current. Ten LDs with low aspect ratio have been operated stably for over 1000 h under 30-mW continuous-wave operation at 60/spl deg/C. Relative intensity noise measured under optical feedback with high-frequency modulation is as low as -125 dB/Hz. These results indicate that this LD is suitable for next-generation high-density optical storage systems.     

Fabrication of room temperature continuous-wave operation GaN-based ultraviolet laser diodes

Two kinds of continuous-wave GaN-based ultraviolet laser diodes (LDs) operated at room temperature and with different emission wavelengths are demonstrated.The LDs epitaxial layers are grown on GaN substrate by metalorganic chemical vapor deposition,with a 10×600 μm2 ridge waveguide structure.The electrical and optical characteristics of the ultraviolet LDs are investigated under direct-current injection at room temperature. The stimulated emission peak wavelength of first LD is 392.9 nm,the threshold current density and voltage is 1.5 kA/cm² and 5.0 V,respectively.The output light power is 80 mW under the 4.0 kA/cm² injection current density. The stimulated emission peak wavelength of second LD is 381.9 nm,the threshold current density the voltage is 2.8 kA/cm² and 5.5 V,respectively.The output light power is 14 mW under a 4.0 kA/cm² injection current density.     

Al-free cladding-layer blue laser diodes with a low aspect ratio in far-field beam pattern

c-plane GaN-based blue laser diodes (LDs) were fabricated with Al-free cladding layers (CLs) and deepened etching depth of mesa structure,so the aspect ratio of the far-field pattern (FFP) of the laser beam can be reduced to as low as 1.7,which is nearly the same as conventional AlGaInP-based red LDs.By using GaN CLs,the radiation angle of the laser beam θ(T) is only 10.1 ° in the direction perpendicular to the junction plane.After forming a deeply etched mesa,the beam divergence angle parallel to the junction plane of FFP,θ//,increases from 4.9° to 5.8°.After using the modified structure,the operation voltage of LD is effectively reduced by 2 V at an injection current of 50 mA,but the threshold current value increases.The etching damage may be one of the main reasons responsible for the increase of the threshold current.     

Behaviors of Emission Wavelength Shift in AlInGaN-Based Green Laser Diodes

InGaN quantum-well (QW) green laser diodes (LDs) with an emission wavelength of 483.7 nm were characterized by controlling the injection pulsewidth. The emission wavelength of LDs showed a large blueshift (> 20 nm) of spontaneous emission peak with increasing injection current below the threshold current. The huge blueshift was ascribed to the deep In localization states and the strong piezoelectric field in the green InGaN QW structure with higher In contents than conventional violet/blue InGaN QWs. However, the lasing wavelength of LDs was slightly redshifted by increasing the injection pulsewidth due to the thermal heating effects.     

Single-mode blue-violet laser diodes with low beam divergence and high COD level

We demonstrate GaN-based high-power single transverse-mode laser diodes (LDs) emitting at 405 nm. LD structures are designed to exhibit a high level of catastrophic optical damage and small beam divergence angle. By the control of refractive index profiles, we achieved a vertical beam divergence angle of as low as 17.5/spl deg/ and maximum output power of as high as 470 mW under continuous-wave operation condition. In addition, nearly fundamental transverse-mode operation is demonstrated up to 500-mW pulsed output power by far-field investigation.     

GaN基蓝光器件的研究进展

本文对近几年ＧａＮ基蓝光器件，包括ＧａＮ基发光二极管和激光二极管的发展历程进行了全面介绍和评价。指出ＧａＮ基蓝光ＬＥＤ的研究开发技术将在１－２年内走向成熟，从而实现大规模商业化生产，而ＧａＮ基蓝光ＬＤ也将在近二年内实用化。     

Gallium-nitride-based materials for blue to ultravioletoptoelectronics devices

Breakthroughs in materials growth have enabled extremely high-efficiency blue and green GaN light emitting diodes (LEDs) to be achieved for the first time. Blue LEDs with external quantum efficiency exceeding 9% have enabled hybrid GaN/phosphor white lamp LEDs. GaN LEDs complete the primary color spectrum and have enabled bright and reliable full-color solid-state displays to be realized. Recently, room-temperature operation of continuous wave current-injection blue-violet lasers emitting at 417 nm has further increased the possible applications for GaN-based opto-electronic devices. In this paper, we review the key technologies for GaN-based materials and devices. Developments in the methods for thin-film deposition by metalorganic chemical vapor deposition and molecular beam epitaxy and resulting film properties are highlighted     

ZnSe基蓝绿色半导体激光器研究进展

在全彩色显示,高密度激光存储,高速打印,高分辨图像处理和战地生化检测等强力推动下,ＺｎＳｅ基蓝绿色半导体激光器的研究近年来取得了里程碑式的研究结果。为了明确该领域的研究方向,以便分析在实用化进程中必须解决的主要问题。本文对ＺｎＳｅ基蓝绿色半导体激光器及其相关材料的研究进展进行了较全面的评述,作为比较,对ＧａＮ基蓝绿色半导体激光器的发展情况和尚待解决的问题也进行了简要评述。