文章基本信息

标题：Strain-stress study of AlxGa1−xN/AlN heterostructures on c-plane sapphire and related optical properties
本地全文：下载
作者：Yining Feng ; Vishal Saravade ; Ting-Fung Chung 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2019
卷号：9
期号：1
页码：1-8
DOI：10.1038/s41598-019-46628-4
出版社：Springer Nature
摘要：This work presents a systematic study of stress and strain of Al x Ga 1-x N/AlN with composition ranging from GaN to AlN, grown on a c-plane sapphire by metal-organic chemical vapor deposition, using synchrotron radiation high-resolution X-ray diffraction and reciprocal space mapping. The c-plane of the Al x Ga 1-x N epitaxial layers exhibits compressive strain, while the a-plane exhibits tensile strain. The biaxial stress and strain are found to increase with increasing Al composition, although the lattice mismatch between the Al x Ga 1-x N and the buffer layer AlN gets smaller. A reduction in the lateral coherence lengths and an increase in the edge and screw dislocations are seen as the Al x Ga 1-x N composition is varied from GaN to AlN, exhibiting a clear dependence of the crystal properties of Al x Ga 1-x N on the Al content. The bandgap of the epitaxial layers is slightly lower than predicted value due to a larger tensile strain effect on the a-axis compared to the compressive strain on the c-axis. Raman characteristics of the Al x Ga 1-x N samples exhibit a shift in the phonon peaks with the Al composition. The effect of strain on the optical phonon energies of the epitaxial layers is also discussed.