Effect of AlN nucleation layer on the structural properties of bulk GaN grown on sapphire by molecular-beam epitaxy

Journal Article · Fri Jul 01 04:00:00 EDT 2005 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.1977189· OSTI ID:20713975

Davidsson, S K; Faelth, J F; Liu, X Y; Zirath, H; Andersson, T G ^[1]

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1. Applied Semiconductor Physics, Molecular-Beam Epitaxy Group (MBE), Department of Microtechnology and Nanoscience, Chalmers University of Technology, S-412 96 Goeteborg (Sweden)

The properties of GaN, grown on sapphire by molecular-beam epitaxy, have been investigated with respect to the properties of the underlying AlN nucleation layer. We show that the AlN thickness and the Al/N flux ratio have pronounced effects on the surface morphology and crystal quality of the GaN overlayer. Low Al/N ratio (<0.4) leads to N-polarity GaN with poor crystal quality. For ratios between 0.4 and 0.7 the surface is smooth with Ga polarity. Higher Al/N flux ratios result in Ga-polar surfaces having plateaus intersected by holes. Optimum values for the GaN(0002) {omega} scan (full width at half maximum of 250 arc sec) and the surface roughness (root mean square of 0.7 nm) were found for a 3-nm-thick AlN nucleation layer (Al/N ratio of 0.6)

• OSTI ID: 20713975
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 1 Vol. 98; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM NITRIDES
CRYSTAL GROWTH
CRYSTALS
GALLIUM NITRIDES
LAYERS
MOLECULAR BEAM EPITAXY
MORPHOLOGY
NUCLEATION
ROUGHNESS
SAPPHIRE
SEMICONDUCTOR MATERIALS
THICKNESS