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Ga N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...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Ga N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 m A和150 m A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.展开更多
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 fabric...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.展开更多
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) n...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.展开更多
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 an...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.展开更多
文摘在发光二极管(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Ga N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 m A和150 m A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.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10774195,U0834001,10974263,11174374,11174061,and 10725420)the Key Program of Ministry of Education,China(Grant No.309024)+1 种基金the New Century Excellent Talents in University,the National Basic Research Program of China(Grant No.2010CB923200)the Natural Science Foundation of Guangdong Province,China(Grant No.S2013010015795)
文摘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.
基金Project supported by the National Natural Science Foundation of China （Grant Nos. 10774195, U0834001, 10974263, 11174374, and 10725420）, the Key Program of Ministry of Education, China （Grant No. 309024）, the Program for New Century Excellent Talents in University of Ministry of Education of China, and the National Basic Research Program of China （Grant No. 2010CB923200）.
文摘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.
基金Project supported by the the National Natural Science Foundation of China (Grant Nos. 10774195, U0834001, 10974263, 11174374, and 10725420)the KeyProgram of Ministry of Education, China (Grant No. 309024)the New Century Excellent Talents in University, and the National Basic Research Program of China (Grant No. 2010CB923200)
文摘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.
