UV Emission from GaN Wires with m-Plane Core-Shell GaN/AlGaN Multiple Quantum Wells
UV Emission from GaN Wires with m-Plane Core-Shell GaN/AlGaN Multiple Quantum Wells
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DOI：
10.1021/acsami.0c08765
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发表时间：
2020-09-30
影响因子：
9.5
通讯作者：
Durand, Christophe
中科院分区：
文献类型：
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作者：
Grenier, Vincent;Finot, Sylvain;Durand, Christophe
本文报道了用金属-有机气相外延技术在条形六方GaN衬底上生长出高质量的非极性GaN/Al0.6Ga0.4N多量子阱(MQW)。光学和结构研究揭示了来自核壳结构的GaN/AlGaN多量子阱的紫外光发射。将m面GaN量子阱厚度从4.3 nm调整到0.7 nm，发射从347 nm移动到292 nm，这与薛定谔-泊松的计算结果一致。发光随温度的变化显示出强烈局域化的迹象，特别是对于GaN量子线较薄的样品，并且没有像非极性m平面表面所预期的那样存在量子受限斯塔克效应的证据。对于2.6 nm厚、发射波长为325 nm的量子阱，由低温和室温下的光致发光强度比得到的(Q)量子效率最大(类似于在低功率激发下测得的7.3%)，而对于较厚的量子阱则表现出较大的下降。对光致发光的温度猝灭进行了深入的研究。两条非辐射复合路径在不同的温度下被激活。研究发现，低温路径是异质结的本征路径，而高温时主导的过程依赖于量子线厚度，并且对于大于2.6 nm的量子线有很强的增强作用，导致内量子效率迅速下降。
The present work reports high-quality nonpolar GaN/Al0.6Ga0.4N multiple quantum wells (MQWs) grown in core-shell geometry by metal-organic vapor-phase epitaxy on the m-plane sidewalls of (c) over bar -oriented hexagonal GaN wires. Optical and structural studies reveal ultraviolet (UV) emission originating from the core-shell GaN/AlGaN MQWs. Tuning the m-plane GaN QW thickness from 4.3 to 0.7 nm leads to a shift of the emission from 347 to 292 nm, consistent with Schrodinger-Poisson calculations. The evolution of the luminescence with temperature displays signs of strong localization, especially for samples with thinner GaN QWs and no evidence of quantum-confined Stark effect, as expected for nonpolar m-plane surfaces. The internal (q)uantum efficiency derived from the photoluminescence (PL) intensity ratio at low and room temperatures is maximum (similar to 7.3% measured at low power excitation) for 2.6 nm thick quantum wells, emitting at 325 nm, and shows a large drop for thicker QWs. An extensive study of the PL quenching with temperature is presented. Two nonradiative recombination paths are activated at different temperatures. The low-temperature path is found to be intrinsic to the heterostructure, whereas the process that dominates at high temperature depends on the QW thickness and is strongly enhanced for QWs larger than 2.6 nm, causing a rapid decrease in the internal quantum efficiency.