Super-aligned carbon nanotubes patterned sapphire substrate to improve quantum efficiency of InGaN/GaN light-emitting diodes.
Super-aligned carbon nanotubes patterned sapphire substrate to improve quantum efficiency of InGaN/GaN light-emitting diodes.
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DOI：
10.1364/oe.23.00a957
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发表时间：
2015-07
期刊：
影响因子：
3.8
通讯作者：
L. Shan;T. Wei;Yuanping Sun;Yong-Hang Zhang;Aigong Zhen;Zhuo-Chun Xiong;Yang Wei;G. Yuan;Junxi Wang;Jinmin Li
中科院分区：
文献类型：
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作者：
L. Shan;T. Wei;Yuanping Sun;Yong-Hang Zhang;Aigong Zhen;Zhuo-Chun Xiong;Yang Wei;G. Yuan;Junxi Wang;Jinmin Li
本文采用金属有机物化学气相沉积（MOCVD）技术在蓝宝石衬底上制备了高性能GaN基发光二极管（LED）。通过对碳纳米管成核机理的研究，分析了不同生长过程中碳纳米管诱导晶体质量提高的原因。结合低温光致发光（PL）测量和二维时域有限差分（FDTD）模拟结果，我们认为CNPSS的光学和电学性能的改善主要来源于纳米外延生长过程中位错密度的降低导致的内量子效率（IQE）的提高。此外，为了降低碳纳米管的光吸收特性，在氧气环境下进行不同时间的退火以去除部分碳纳米管。在350 mA电流注入下，退火2 h和10 h的CNPSS-LED的光输出功率（LOP）分别比未退火的CNPSS-LED提高了11%和6%。因此，高温退火可以有效地去除部分碳纳米管，进一步提高LOP，而过长的退火时间会导致量子阱的退化，导致光功率的衰减。
In this paper, the high performance GaN-based light-emitting diodes (LEDs) on carbon-nanotube-patterned sapphire substrate (CNPSS) by metal-organic chemical vapor deposition (MOCVD) are demonstrated. By studying the mechanism of nucleation, we analyze the reasons of the crystal quality improvement induced by carbon nanotubes (CNTs) in different growth process. Combining with low temperatures photoluminescence (PL) measurements and two-dimensional (2D) finite difference time-domain (FDTD) simulation results, we conclude that the improvement of optical properties and electrical properties of CNPSS mainly originates from the improvement of the internal quantum efficiency (IQE) due to decreased dislocation density during nano-epitaxial growth on CNPSS. Additionally, in order to reduce the light absorption characteristics of CNTs, different time annealing under the oxygen environment is carried out to remove part of CNTs. Under 350 mA current injections, the light output power (LOP) of CNPSS-LED annealed 2 h and 10 h exhibit 11% and 6% enhancement, respectively, compared to that of the CNPSS-LED without annealing. Therefore, high temperature annealing can effectively remove parts of CNTs and further increase the LOP, while overlong annealing time has caused degradation of the quantum well resulting in the attenuation of optical power.