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The effect of silver nanostructures prepared by nanosphere lithography on the photoluminescence(PL) properties of blue-emitting In Ga N/Ga N quantum wells(QWs) is studied. Arrays of silver nanoparticles are fabricated to yield a collective surface plasmonic resonance(SPR) near to the QWs emission wavelength. A large enhancement in peak PL intensity is observed, when the induced SPR wavelength of the nanoparticles on the QWs sample matches the QWs emission wavelength. The study proves that the SPRs could enhance the light emission efficiency of semiconductor material.  相似文献   
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基于声透镜成像系统的光声层析成像   总被引:4,自引:0,他引:4       下载免费PDF全文
陈湛旭  唐志列  万巍  何永恒 《物理学报》2006,55(8):4365-4370
光声成像是采用“光激发-超声波成像”的新型成像技术,它是检测强散射介质内部光吸收分布的一种有效医学影像技术.用短脉冲激光照射强散射介质(如生物组织),强散射介质由于光声效应产生超声信号,使用具有成像能力的声透镜把声压分布成像于像面上,然后利用具有空间分辨能力的阵列光声传感器,把同一像面上的光声信号强度记录下来,最后根据光声信号强度的空间分布进行图像重组.根据成像系统物像共轭原理,同一物平面的光声信号到达像面的时延相等,而不同物面的光声信号到达同一个探测器平面的时延各不相同,因此,利用BOXCAR的门控积分 关键词: 光声层析成像 声透镜 光声信号  相似文献   
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光声光谱技术在测量光谱响应特性方面的应用   总被引:1,自引:0,他引:1  
用光声光谱技术测量光电探测器的相对光谱响应特性,以高灵敏度的光声池(池内装有吸收系数约为1的碳黑)作为参考探测器,具有较好的波长无选择性。用碳黑监测光源功率,减少光源功率起伏误差。采用二次测量归一化方法避免了分束器的影响。实验测得了比较准确的相对光谱响应特性曲线,为研究光电探测器的特性提供了一种可行的方法。  相似文献   
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We demonstrate the fabrication of hexagonal nano-pillar arrays at the surface of GaN-based light-emitting diodes (LEDs) by nanosphere lithography. By varying the oxygen plasma etching time, we could tune the size and shape of the pillar. The nano-pillar has a truncated cone shape. The nano-pillar array serves as a gradual effective refractive index matcher, which reduces the reflection and increases light cone. It is found that the patterned surface absorbs more pumping light. To compare extraction efficiencies of LEDs, it is necessary to normalize the photoluminescence power spectrum with total absorption rate under fixed pumping power, then we could obtain the correct enhancement factor of the photoluminescence extraction efficiency and optimized structure. The highest enhancement factor of the extraction efficiency is 10.6.  相似文献   
5.
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 lithog- raphy; 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 en- hancement 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   
6.
陈湛旭  万巍  何影记  陈耿炎  陈泳竹 《物理学报》2015,64(14):148502-148502
在发光二极管(LED)的透明电极层上制作单层六角密排的聚苯乙烯(polystyrene, PS) 纳米球, 研究提高GaN基蓝光LED的出光效率. 采用自组装的方法在透明电极铟锡氧化物层上制备了直径分别约为250, 300, 450, 600和950 nm的PS纳米球, 并且开展了电致发光的研究. 结果表明, 在LED的透明电极层上附有PS纳米球能有效地提高LED的出光效率; 当PS纳米球的直径与出射光的波长比较接近时, LED的出光效率最优. 与参考样品相比, 在20 mA和150 mA工作电流下, 附有PS纳米球的样品的发光效率分别增加1.34倍和1.25倍. 三维时域有限差分方法计算表明, 该出光增强主要归因于附有PS纳米球的LED结构可以增大LED结构的光输出临界角, 从而提高LED的出光效率. 因此, 这是一种低成本的实现高效率LED的方法.  相似文献   
7.
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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