Cathodoluminescence spectroscopy of epitaxial-lateral-overgrown nonpolar (11-20) and semipolar (11-22) GaN in relation to microstructural characterization
Cathodoluminescence spectroscopy of epitaxial-lateral-overgrown nonpolar (11-20) and semipolar (11-22) GaN in relation to microstructural characterization
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DOI：
10.1063/1.2740361
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发表时间：
2007-06-01
影响因子：
3.2
通讯作者：
Albrecht, M.
中科院分区：
文献类型：
--
作者：
Guhne, T.;Bougrioua, Z.;Albrecht, M.
采用ELO技术在R型和M型单晶上分别生长了非极性（11-20）和半极性（11-22）取向的GaN薄膜，并对其进行了低温空间分辨阴极发光研究。缺陷相关的光学跃迁进行了鉴定，其本地化相关的ELO的不同区域。通过平面和横截面透射电子显微镜进一步研究了样品的微观结构。结果表明，与缺陷相关的发射主要集中在样品的种子中，但不同的缺陷也发生在翅膀，特别是在非极性GaN的情况下。在半极性GaN的过度生长翼中，结构缺陷密度最低。特别是，[0001]翼区的半极性的x-GaN几乎是无缺陷的阴极发光光谱占主导地位的GaN带边发射在3.476 eV。(c)2007年，美国物理学会。
Low temperature spatially resolved cathodoluminescence was carried out on GaN films grown by the epitaxial-lateral-overgrowth (ELO) technique with the nonpolar (11-20) and the semipolar (11-22) orientations on R- and M-sapphires, respectively. Defect related optical transitions were identified and their localization was correlated to different regions of ELO. The sample microstructure was further investigated by plan-view and cross-section transmission electron microscopies. It is shown that the defect related emissions are mainly localized in the seed of the samples, but different defects occur as well in the wings, especially in the case of nonpolar GaN. The structural defect densities are lowest in the overgrown wings of semipolar GaN. In particular, the [0001] wing region of semipolar ELO-GaN is almost defect-free with a cathodoluminescence spectrum dominated by the GaN band-edge emission at 3.476 eV. (c) 2007 American Institute of Physics.