Influence of the AlGaN buffer layer on the biaxial strain of GaN epilayers grown on 6H-SiC (0001) by molecular-beam epitaxy
- Power Electronics Research Center, National Institute of Advanced Industrial Science and Technology, Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)
The role of Al{sub x}Ga{sub 1-x}N buffers in the control of residual strain in GaN epitaxial layers grown on 6H-SiC (0001) substrates by molecular-beam epitaxy was investigated. The initial GaN layer on the Al{sub x}Ga{sub 1-x}N (x=0%-10%) buffer nucleates in two-dimensional form, which promotes a step-flow growth mode in subsequently grown GaN layers. As the Al content in the Al{sub x}Ga{sub 1-x}N (x{approx}20%) buffer was increased, GaN began to nucleate as incoherent polygonal islands, coalescing as the thickness increased to 15 nm. The overall residual strain induced in GaN is tensile ({epsilon}{sub xx}) for GaN grown directly on SiC and compressive (-{epsilon}{sub xx}) for GaN grown using an AlGaN buffer. The stiffness coefficient (-2C{sub 13}/C{sub 33}) of GaN on the Al{sub x}Ga{sub 1-x}N (x{approx}10%) buffer was estimated to be -0.53 assuming that the defect-induced hydrostatic stress of unstrained GaN (c{sub 0}/a{sub 0}) was constant.
- OSTI ID:
- 20664961
- Journal Information:
- Journal of Applied Physics, Vol. 97, Issue 1; Other Information: DOI: 10.1063/1.1826219; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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