Light emission and microstructure of Mg-doped AlGaN grown on patterned sapphire
Light emission and microstructure of Mg-doped AlGaN grown on patterned sapphire
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DOI：
10.1063/1.1537517
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发表时间：
2003-01-20
影响因子：
4
通讯作者：
Cherns, D
中科院分区：
文献类型：
--
作者：
Bell, A;Liu, R;Cherns, D
在蓝宝石衬底上生长的Mg掺杂的Al 0.03 Ga 0.97 N中观察到了独特的晶体和光学性质;该图案由沿着蓝宝石方向的蚀刻沟槽组成。外延层有两个不同的区域：一个直接生长在蓝宝石梅萨上，另一个是悬在沟槽上方的外延横向过生长（ELO）区域。透射电子显微镜显示存在的金字塔缺陷，以及大的位错密度直接生长在蓝宝石上的区域。相比之下，ELO区域是无缺陷的并且不包含Mg相关的锥体缺陷。阴极发光测量显示在ELO区域中的上级近带边发射，这表明发射对由样品的其余部分中的高缺陷密度引起的非辐射中心敏感。Mg相关的施主-受主对发射在整个薄膜中是相当均匀的，表明它不受非辐射中心的影响。AlGaN的这些光学和结构性质与生长前沿的方向密切相关。(C)2003年，美国物理学会。
Distinct crystalline and optical properties have been observed in Mg-doped Al0.03Ga0.97N grown on a patterned sapphire substrate; the pattern consisting of etched trenches along the sapphire direction. The epilayer has two distinct regions: one grown directly onto the sapphire mesa and the other an epitaxial lateral overgrowth (ELO) region that overhangs the trench. Transmission electron microscopy shows the presence of pyramidal defects as well as large dislocation densities in the region grown directly on sapphire. In contrast, the ELO region is defect free and contains no Mg-related pyramidal defects. Cathodoluminescence measurements show superior near-band-edge emission in the ELO region, suggesting that the emission is susceptible to nonradiative centers caused by the high defect density in the rest of the sample. The Mg-related donor-acceptor-pair emission is fairly uniform throughout the film, indicating that it is not affected by the nonradiative centers. These optical and structural properties of AlGaN are closely related to the direction of the growth front. (C) 2003 American Institute of Physics.