Strain-stress study of AlxGa1-xN/AlN heterostructures on c-plane sapphire and related optical properties.
In: Scientific reports, Jg. 9 (2019-07-15), Heft 1
academicJournal
- 10172
Zugriff:
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.
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Strain-stress study of AlxGa1-xN/AlN heterostructures on c-plane sapphire and related optical properties.
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Autor/in / Beteiligte Person: | Feng, Yining ; Saravade, Vishal ; Chung, Ting-Fung ; Dong, Yongqi ; Zhou, Hua ; Kucukgok, Bahadir ; Ferguson, Ian T ; Lu, Na |
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Zeitschrift: | Scientific reports, Jg. 9 (2019-07-15), Heft 1 |
Veröffentlichung: | eScholarship, University of California, 2019 |
Medientyp: | academicJournal |
Umfang: | 10172 |
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