Title: X-ray crystallographic study of GaN epitaxial films on Al2O3(0001) substrates with GaN buffer layers
Authors: Lee, CH
Chi, GC
Lin, CF
Feng, MS
Guo, JD
Department of Materials Science and Engineering
Department of Electronics Engineering and Institute of Electronics
Issue Date: 10-Jun-1996
Abstract: Samples of GnN(0001) epitaxial films on sapphire Al2O3(0001) with different thicknesses of GaN buffer layers were characterized by x-ray diffraction method in both in-plane and plane-normal directions. The results show that all the epitaxial films Me of good quality with the GaN[<10(1)over bar 0>] parallel to Al2O3[<11(2)over bar 0>] and GaN[<1(2)over bar 10>]parallel to Al2O3[<1(1)over bar 00>]. This arrangement of crystal orientation can be attributed to the chemical potential overriding the lattice spacing mismatch. The x-my results also indicate that the crystal coherence lengths; in the in-plane direction are smaller than those measured in the plane-normal direction, i.e., a columnar-like structure normal to the film is observed; The rocking curve widths in the in-plane direction are also larger than those measured in the plane-normal direction. In-plane measurement of rocking curve and coherence length are essential physical quantities directly related to the electron mobility which was measured predominantly in the in-plane direction. The best epitaxial structure is the one grown with 10 nm buffer layer. (C) 1996 American Institute of Physics.
URI: http://dx.doi.org/10.1063/1.115786
ISSN: 0003-6951
DOI: 10.1063/1.115786
Volume: 68
Issue: 24
Begin Page: 3440
End Page: 3442
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