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Microstructure and Strain-Free Lattice Parameters of ScGaN Films

Published online by Cambridge University Press:  01 February 2011

Michelle Anna Moram
Affiliation:
mam65@cam.ac.uk, University of Cambridge, Dept. Materials Science & Metallurgy, Pembroke St, Cambridge, N/A, CB2 3QZ, United Kingdom, 44 7765780182, 44 1223 334373
Timothy B Joyce
Affiliation:
t.joyce@liverpool.ac.uk, University of Liverpool, Dept. Engineering, United Kingdom
Paul R Chalker
Affiliation:
pchalker@liverpool.ac.uk, University of Liverpool, Dept. Engineering, United Kingdom
Zoe H Barber
Affiliation:
zb10@cam.ac.uk, University of Cambridge, Dept. Materials Science & Metallurgy, United Kingdom
Colin J Humphreys
Affiliation:
colin.humphreys@msm.cam.ac.uk, University of Cambridge, Dept. Materials Science & Metallurgy, United Kingdom
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Abstract

Epitaxial ScxGa1-xN films of low Sc concentration (x = 0.08 ± 0.01) were deposited on MOCVD-grown GaN films (using an Al2O3 substrate) at 800°C using molecular beam epitaxy employing ammonia as a reactive nitrogen source (NH3-MBE). The strain-free lattice parameters of the films were determined using a method based on high-resolution X-ray diffraction (HRXRD) in conjunction with an in-situ elastic tester. It is found that the c:a lattice parameter ratio increases slightly and that the Poisson’s ratio decreases with increasing Sc concentration. The crystalline quality and long-range ordering of the ScxGa1-xN films (as indicated by HRXRD peak intensities and full width at half maximum values) is improved considerably relative to the GaN template. Our results indicate that threading dislocations do not propagate effectively into the ScxGa1-xN films and that these may therefore potentially find application as dislocation blocking layers in GaN-based optoelectronic devices.

Type
Research Article
Copyright
Copyright © Materials Research Society 2006

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References

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