Influence of the AlGaN buffer layer on the biaxial strain of GaN epilayers grown on 6H-SiC (0001) by molecular-beam epitaxy

Journal Article · Sat Jan 01 04:00:00 EST 2005 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.1826219· OSTI ID:20664961

Jeganathan, K; Shimizu, M; Okumura, H ^[1]

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1. 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, Journal Name: Journal of Applied Physics Journal Issue: 1 Vol. 97; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM COMPOUNDS
BUFFERS
CRYSTAL DEFECTS
CRYSTAL GROWTH
FLEXIBILITY
GALLIUM NITRIDES
LAYERS
MAGNETIC ISLANDS
MOLECULAR BEAM EPITAXY
NUCLEATION
SEMICONDUCTOR MATERIALS
SILICON CARBIDES
STRAINS
STRESSES
SUBSTRATES
THICKNESS