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Growth, microstructure and morphology of epitaxial ScGaN films
Author(s) -
Knoll S. M.,
Zhang S.,
Joyce T. B.,
Kappers M. J.,
Humphreys C. J.,
Moram M. A.
Publication year - 2012
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201100158
Subject(s) - sapphire , materials science , wurtzite crystal structure , epitaxy , coalescence (physics) , molecular beam epitaxy , crystallography , microstructure , dislocation , diffraction , photoluminescence , luminescence , analytical chemistry (journal) , layer (electronics) , composite material , optoelectronics , optics , chemistry , hexagonal crystal system , laser , physics , chromatography , astrobiology
Epitaxial ScGaN films were grown on GaN‐on‐sapphire substrates by NH 3 ‐molecular beam epitaxy (MBE). The Sc content remained below 2% for all films, as determined by the simulation and fitting of 0002 ω –2 θ X‐ray diffractograms, while no deviation from the wurtzite structure was detected using high resolution X‐ray diffraction. ScGaN growth rates decreased significantly as the Sc flux increased and remained low compared to the growth rates of GaN grown under similar conditions, while Sc incorporation rates remained low even at Sc effusion cell temperatures as high as 1400 °C. Atomic force microscopy (AFM) height images indicate that higher Sc fluxes are associated with improved film coalescence. These data indicate that a surfactant layer of Sc may be present at the film surface during growth. The dislocation density of the lower Sc content films was similar to that of the underlying GaN, though the bending and introduction of additional dislocations with an a ‐component was observed for higher Sc contents. Basal plane stacking faults connected by prismatic stacking faults were also observed, in higher Sc‐content ScGaN films, along with a broad luminescence band near 580 nm.