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《发光学报》2021,42(4)
为了提高氮化镓(GaN)基发光二极管(LEDs)的发光性能,采用等离子体增强化学气相沉积(PECVD)在蓝宝石衬底上沉积SiO_2薄膜,经过光刻和干法刻蚀技术制备了SiO_2图形化蓝宝石衬底(SiO_2 patterned sapphire substrate, SPSS),利用LED器件的外延生长和微纳加工技术获得了基于SPSS的GaN基LED器件。通过分析GaN外延层晶体质量、光提取效率和LED器件性能,重点研究了SPSS对GaN生长及LED发光性能的影响。实验及模拟仿真结果表明,与常规图形化蓝宝石衬底(Conventional patterned sapphire substrate, CPSS)相比,SPSS上生长的GaN外延层位错密度较低,晶体质量较高,SPSS-LED的光提取效率提高26%、光输出功率和亮度均提高约5%。 相似文献
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利用金属有机气相化学沉积(MOCVD)技术在蓝宝石图形衬底上生长GaN基蓝光LED,并系统研究了不同中高温GaN插入层厚度对其光电性能的影响。利用芯片测试仪和原子力显微镜(AFM)表征了GaN基蓝光LED外延片的光电性能以及表面形貌。当中高温GaN插入层厚度从60 nm增加至100 nm时,V形坑尺寸从70~110 nm增加至110~150 nm。当注入电流为20 mA时,LED芯片的光功率从21.9 mW增加至24.1mW;当注入电流为120 mA时,LED芯片的光功率从72.4 mW增加至82.4 mW。对V形坑尺寸调控LED光电性能的相关物理机制进行了分析,结果表明:增大V形坑尺寸有利于增加空穴注入面积和注入效率,进而提高LED器件的光功率。 相似文献
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转移基板材质对Si衬底GaN基LED芯片性能的影响 总被引:7,自引:4,他引:3
在Si衬底上生长了GaN基LED外延材料,分别转移到新的硅基板和铜基板上,制备了垂直结构蓝光LED芯片。研究了这两种基板GaN基LED芯片的光电性能。在切割成单个芯片之前,对大量尺寸为(300μm×300μm)的这两种芯片分别通高达1 A的大电流在测试台上加速老化1 h。结果显示,铜基板Si衬底GaN基LED芯片有更大的饱和电流,光输出效率更高,工作电压随驱动电流的变化不大,光输出在老化过程中衰减更小。铜基板芯片比硅基板芯片可靠性更高,在大功率半导体照明器件中前景诱人。 相似文献
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为了提高GaN基发光二极管(LED)的外量子效率,在蓝宝石衬底制作了二维光子晶体.衬底上的二维光子晶体结构采用激光全息技术和感应耦合等离子体(ICP)干法刻蚀技术制作,然后采用金属氧化物化学气相沉积(MOCVD)技术在图形蓝宝石衬底(PSS)上生长2μm厚的n型GaN层,4层量子阱和200nm厚的p型GaN层,形成LED结构.衬底上制作的二维光子晶体为六角晶格结构,晶格常数为3.8μm,刻蚀深度为800nm.LED器件光强输出测试结果显示,在PSS上制作的LED(PSS-LED)的发光强度普遍高于蓝宝石平
关键词:
全息
发光二极管
图形蓝宝石衬底
外量子效率 相似文献
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在柱状图形蓝宝石衬底(PSS-p)和孔状图形蓝宝石衬底(PSS-h)上外延了GaN体材料和LED结构并进行了详细对比和分析.X射线衍射仪(XRD)和原子力显微镜(AFM)测试结果表明,PSS-h上体材料的晶体质量和表面形貌都优于PSS-p上体材料的特性,通过断面扫面电子显微镜(SEM)照片看出PSS-h上GaN的侧向生长是导致这种差异的原因.另外,基于PSS-p和PSS-h上外延的LED材料制作而成的器件结果表明,其20?mA下光功率水平相比普通蓝宝石衬底(CSS)分别提高了46%和33%.通过变温光荧光
关键词:
蓝宝石图形衬底
氮化镓
发光二极管
侧向生长 相似文献
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《中国物理 B》2015,(6)
The influence of buffer layer growth conditions on the crystal quality and residual stress of GaN film grown on silicon carbide substrate is investigated.It is found that the Al GaN nucleation layer with high growth temperature can efficiently decrease the dislocation density and stress of the GaN film compared with Al N buffer layer.To increase the light extraction efficiency of GaN-based LEDs on Si C substrate,flip-chip structure and thin film flip-chip structure were designed and optimized.The fabricated blue LED had a maximum wall-plug efficiency of 72% at 80 m A.At 350 m A,the output power,the Vf,the dominant wavelength,and the wall-plug efficiency of the blue LED were 644 m W,2.95 V,460 nm,and 63%,respectively. 相似文献
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We theoretically analyze the improvement in light extraction efficiency (LEE) of GaN-based LEDs with transmission grating. Light propagation and extraction was simulated using the finite-difference time-domain (FDTD) method for conical, cylindrical, and hemispherical grating. The simulations show that the use of transmission grating leads to increase in the LEE of GaN-based LEDs. The enhancement in LEE is attributed to the decrease in the Fresnel reflection and the effective increase in the photon escape cone. The maximum LEE enhancement of 2.3 times was achieved by employing hemispherical grating. The directional emission pattern converged by employing conical grating. 相似文献
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Xiaomin Jin Bei Zhang Tao Dai Wei Wei Xiangning Guoyi Zhang Simeon Trieu Fei Wang 《中国光学快报(英文版)》2008,6(10)
We present a grating model of two-dimensional (2D) rigorous coupled wave analysis (RCWA) to study top diffraction gratings on light-emitting diodes(LEDs). We compare the integrated-transmission of the non-grating,rectangular-grating,and triangular-grating cases for the same grating period of 6μm,and show that the triangular grating has the best performance. For the triangular grating with 6-μmperiod, the LED achieves the highest light transmission at 6-μ gratingbottom width and 2.9-μm grating depth. Compared with the non-grating case, the optimized light transmission improvement is about 74.6%.The simulation agrees with the experimental data of the thin ploymer grating encapsulated flip-chip(FC) GaN-based LEDs for the light extraction improvement. 相似文献
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《中国物理 B》2015,(6)
Progress with GaN-based light emitting diodes(LEDs) that incorporate nanostructures is reviewed,especially the recent achievements in our research group.Nano-patterned sapphire substrates have been used to grow an Al N template layer for deep-ultraviolet(DUV) LEDs.One efficient surface nano-texturing technology,hemisphere-cones-hybrid nanostructures,was employed to enhance the extraction efficiency of In GaN flip-chip LEDs.Hexagonal nanopyramid GaN-based LEDs have been fabricated and show electrically driven color modification and phosphor-free white light emission because of the linearly increased quantum well width and indium incorporation from the shell to the core.Based on the nanostructures,we have also fabricated surface plasmon-enhanced nanoporous GaN-based green LEDs using AAO membrane as a mask.Benefitting from the strong lateral SP coupling as well as good electrical protection by a passivation layer,the EL intensity of an SP-enhanced nanoporous LED was significantly enhanced by 380%.Furthermore,nanostructures have been used for the growth of GaN LEDs on amorphous substrates,the fabrication of stretchable LEDs,and for increasing the3-d B modulation bandwidth for visible light communication. 相似文献
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《中国物理 B》2015,(6)
A new method for patterned sapphire substrate(PSS) design is developed and proven to be reliable and cost-effective.As progress is made with LEDs' luminous efficiency,the pattern units of PSS become more complicated,and the effect of complicated geometrical features is almost impossible to study systematically by experiments only.By employing our new method,the influence of pattern parameters can be systematically studied,and various novel patterns are designed and optimized within a reasonable time span,with great improvement in LEDs' light extraction efficiency(LEE).Clearly,PSS pattern design with such a method deserves particular attention.We foresee that GaN-based LEDs on these newly designed PSSs will achieve more progress in the coming years. 相似文献
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Enhancing light extraction of GaN-based blue light-emitting diodes by a tuned nanopillar array 下载免费PDF全文
Surface patterning of p-GaN to improve the light extraction efficiency of GaN-based blue light-emitting diodes(LEDs) has been investigated. Periodic nanopillar arrays on p-GaN have been fabricated by polystyrene(PS) nanosphere lithography; the diameter of the nanopillars can be tuned to optimize the electrical and optical properties of the LEDs. The electroluminescence intensity of the nanopillar-patterned LEDs is better than that of conventional LEDs; the greatest enhancement increased the intensity by a factor of 1.41 at a 20 mA injection current. The enhancements can be explained by a model of bilayer film on a GaN substrate. This method may serve as a practical approach to improve the efficiency of light extraction from LEDs. 相似文献
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W. F. Yang Z. G. Liu Y. N. Xie J. F. Cai S. Liu H. Gong Z. Y. Wu 《Applied Physics A: Materials Science & Processing》2012,107(4):809-812
This letter presents a holographic photonic crystal (H-PhC) Al-doped ZnO (AZO) transparent Ohmic contact layer on p-GaN to increase the light output of GaN-based LEDs without destroying the p-GaN. The operating voltage of the PhC LEDs at 20 mA was almost the same as that of the typical planar AZO LEDs. While the resultant PhC LED devices exhibited significant improvements in light extraction, up to 1.22 times that of planar AZO LEDs without PhC integration. Temperature dependence of the integrated photoluminescence intensity indicates that this improvement can be attributed to the increased extraction efficiency due to the surface modification. These results demonstrate that the surface-treated AZO layer by H-PhCs is suitable for fabricating high-brightness GaN-based LEDs. 相似文献
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LiXia Zhao ShiChao Zhu ChunHui Wu Chao Yang ZhiGuo Yu Hua Yang Lei Liu 《中国科学:物理学 力学 天文学(英文版)》2016,59(10):107301
Rapid improvement in the efficiency of GaN-based LEDs not only speed up its applications for general illumination, but offer the possibilities for data transmission. This review is to provide an overview of current progresses of GaN-based LEDs for light communications. The modulation bandwidth of GaN-based LEDs has been first improved by optimizing the LED epilayer structures and the modulation bandwidth of 73 MHz was achieved at the driving current density of 40 A/cm2 by changing the multi-quantum well structures. After that, in order to increase the current density tolerance, different parallel flip-chip micro-LED arrays were fabricated. With a high injected current density of ~7900 A/cm2, a maximum modulation bandwidth of ~227 MHz was obtained with optical power greater than 30 mW. Besides the increase of carrier concentrations, the radiative recombination coefficient B was also enhanced by modifying the photon surrounding environment based on some novel nanostructures such as resonant cavity, surface plasmon, and photonic crystals. The optical 3 dB modulation bandwidth of GaN-based nanostructure LEDs with Ag nanoparticles was enhanced by 2 times compared with GaN-based nanostructure LEDs without Ag nanoparticles. Our results demonstrate that using the QW-SP coupling can effectively help to enhance the carrier spontaneous emission rate and also increase the modulation bandwidth for LEDs, especially for LEDs with high intrinsic IQE. In addition, we discuss the progress of the faster color conversion stimulated by GaN-based LEDs. 相似文献
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定性分析了GaN基LED的电流扩展效应,发现电流密度和电流横向扩展的有效长度对电流均匀扩展有很大影响.基于此,对GaN基大功率LED提出了优化的电极结构,以减缓电流拥挤效应,降低器件串联电阻.通过用红外热像仪测量器件表面的温度分布,发现具有优化的环形插指电极结构的GaN基大功率LED表面温度分布比较均匀,证明芯片接触处电流扩展均匀,局部电流密度降低,减小了焦耳热的产生,增强了器件的可靠性.
关键词:
氮化镓
发光二极管
电流扩展
电极结构优化 相似文献