Diameter-dependent photoluminescence properties of strong phase-separated dual-wavelength InGaN/GaN nanopillar LEDs
Diameter-dependent photoluminescence properties of strong phase-separated dual-wavelength InGaN/GaN nanopillar LEDs
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强相分离双波长 InGaN/GaN 纳米柱 LED 的直径相关光致发光特性
DOI：
10.1016/j.apsusc.2017.03.093
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发表时间：
2017
影响因子：
6.7
通讯作者：
Leng Jiancai
中科院分区：
文献类型：
--
作者：
Wang Qiang;Ji Ziwu;Zhou Yufan;Wang Xuelin;Liu Baoli;Xu Xiangang;Gao Xingguo;Leng Jiancai
在本文中，采用聚焦离子束刻蚀技术制备了具有相同 NP 密度和不同 NP 直径的强相分离蓝/绿双波长 InGaN/GaN 纳米柱 (NP) 发光二极管 (LED)。显微拉曼光谱用于显示纳米粒子直径对多量子阱 (MQW) 中应变弛豫的影响。首次利用微光致发光 (PL) 光谱研究了 NP 直径对强相分离双波长 InGaN/GaN NP LED 光学行为的影响。 NP LED 的 PL 峰值能量蓝移表明，直径较小的 NP LED 在 MQW 中表现出较大的应变弛豫，微拉曼结果证实了这一点。并且绿光发射的蓝移小于蓝光发射的蓝移。由于重组率和光提取效率增加，与生长的样品相比，NP 阵列的总集成 PL 强度有所增强。在我们的实验中，增强因子随着NP直径的减小而减小，这表明与复合率和光提取效率的增加相比，活性体积的损失逐渐对NP LED的发光效率产生主导作用。
In this paper, strong phase-separated blue/green dual-wavelength InGaN/GaN nanopillar (NP) light emitting diodes (LEDs) with the same NP density and various NP diameters were fabricated using focused ion beam etching. Micro-Raman spectroscopy was used to show the effect of NP diameter on the strain relaxation in the multi-quantum-wells (MQWs). The effect of NP diameter on optical behaviors of the strong phase-separated dual-wavelength InGaN/GaN NP LEDs was investigated for the first time by using micro-photoluminescence (PL) spectroscopy. The blue shifts of PL peak energies of the NP LEDs showed that the NP LED with a smaller diameter exhibited a larger strain relaxation in the MQWs, as confirmed by micro-Raman results. And the blue shift of green emission was smaller than that of blue emission. The total integrated PL intensities from the NP arrays were enhanced compared to the as-grown sample due to the increased recombination rate and light extraction efficiency. The enhancement factor decreased with decreasing the NP diameter in our experiments, which indicated that the loss of active volume was gradually dominant for the luminous efficiency of NP LEDs compared to the increased recombination rate and light extraction efficiency.