Abstract
This work presents a systematic study of stress and strain of AlxGa1−xN/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 AlxGa1−xN 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 AlxGa1−xN 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 AlxGa1−xN composition is varied from GaN to AlN, exhibiting a clear dependence of the crystal properties of AlxGa1−xN 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 AlxGa1−xN 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.
Recommended Citation
Y. Feng et al., "Strain-Stress Study of AlxGa1−xN/AIN Heterostructures on C-Plane Sapphire and Related Optical Properties," Scientific Reports, vol. 9, no. 1, article no. 10172, Nature Research, Dec 2019.
The definitive version is available at https://doi.org/10.1038/s41598-019-46628-4
Department(s)
Electrical and Computer Engineering
Publication Status
Open Access
International Standard Serial Number (ISSN)
2045-2322
Document Type
Article - Journal
Document Version
Final Version
File Type
text
Language(s)
English
Rights
© 2024 The Authors, All rights reserved.
Creative Commons Licensing
This work is licensed under a Creative Commons Attribution 4.0 License.
Publication Date
01 Dec 2019
PubMed ID
31308418
Comments
Purdue University, Grant CMMI – 1560834