Si concentration dependence of structural inhomogeneities in Si-doped AlxGa1-xN/AlyGa1-yN multiple quantum well structures (x=0.6) and its relationship with internal quantum efficiency
Si concentration dependence of structural inhomogeneities in Si-doped AlxGa1-xN/AlyGa1-yN multiple quantum well structures (x=0.6) and its relationship with internal quantum efficiency
复制标题
Si掺杂AlxGa1-xN/AlyGa1-yN多量子阱结构(x=0.6)中结构不均匀性的Si浓度依赖性及其与内量子效率的关系
DOI：
10.1063/1.4904847
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发表时间：
2014
影响因子：
3.2
通讯作者：
Y.Yamada
中科院分区：
文献类型：
--
作者：
S.Kurai;K.Anai;H.Miyake;K.Hiramatsu;Y.Yamada
利用阴极发光（CL）技术结合扫描电子显微镜（SEM）研究了不同Si掺杂浓度的Al{sub x}Ga {sub 1−x}N/Al{sub y}Ga{sub 1−y}N多量子阱（MQW）结构（x = 0.6）的发光分布。研究了表面形貌、暗斑密度和半峰全宽对内量子效率的影响。与未掺杂的AlGaN MQW和具有相对低Al含量的Si掺杂的AlGaN相比，Si掺杂的AlGaN MQW观察到平坦的表面形貌和均匀的CL图。在Si掺杂的AlGaN多量子阱中的暗点密度随着Si浓度的增加而呈指数增加，并且不能解释IQE的Si浓度依赖性。相比之下，在恒定的Si浓度下，AlGaN多量子阱的暗点密度和IQE之间存在明显的相关性。由相对Al含量和阱层厚度的不均匀性引起的发射能量分布估计由单色CL测量，虽然对于不同Si浓度的分布几乎没有差异。因此，先前报道的缺陷复合物对Si浓度的依赖性反映在Si掺杂的AlGaN多量子阱的IQE中。由阳离子空位和杂质组成的缺陷复合物而不是位错和界面质量是影响不同Si浓度的Si掺杂AlGaN多量子阱的量子效率的主要因素。
We investigated the distribution of luminescence in Si-doped Al{sub x}Ga{sub 1−x}N/Al{sub y}Ga{sub 1−y}N multiple quantum well (MQW) structures (x = 0.6) with different Si concentrations by cathodoluminescence (CL) mapping combined with scanning electron microscopy. The effects of surface morphology, dark spot density, and full width at half-maximum of spot CL spectra on internal quantum efficiency (IQE) were determined. A flat surface morphology and uniform CL map were observed for Si-doped AlGaN MQWs, in contrast to undoped AlGaN MQW and Si-doped AlGaN with relatively low Al content. The dark spot density in the Si-doped AlGaN MQWs increased exponentially as the Si concentration increased and did not explain the Si concentration dependence of IQE. In contrast, there was a clear correlation between the dark spot density and IQE of the AlGaN MQWs at a constant Si concentration. The emission energy distribution arising from the inhomogeneity of the relative Al content and the well layer thickness was estimated by monochromatic CL measurements, although there was almost no difference in the distribution for different Si concentrations. Therefore, the previously reported dependence of the defect complexes on Si concentration is reflected in the IQE of Si-doped AlGaN MQWs. Defect complexes composed of cation vacancies and impurities rather than dislocations and interfacial quality are the major contributor to the IQE of the Si-doped AlGaN MQWs with different Si concentrations.