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Author Smith, Arthur R. ♦ AL-Brithen, Hamad A. H. ♦ Ingram, David C. ♦ Gall, Daniel
Sponsorship (US)
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Publisher The American Physical Society
Language English
Subject Keyword MATERIALS SCIENCE ♦ ABSORPTION ♦ CARRIER DENSITY ♦ DIFFUSION ♦ ELECTRIC CONDUCTIVITY ♦ MAGNESIUM OXIDES ♦ MOLECULAR BEAM EPITAXY ♦ MORPHOLOGY ♦ OPTICAL REFLECTION ♦ PHYSICS ♦ SCANDIUM ♦ SCANDIUM NITRIDES ♦ SUBSTRATES
Abstract Scandium nitride (001) oriented layers have been grown on magnesium oxide (001) substrates by molecular beam epitaxy using a rf-plasma source and a scandium effusion cell. The Sc/N flux ratio is found to be critical in determining the structural, optical, and electronic properties of the grown epitaxial layers. A distinct transition occurs at the point where the Sc/N flux ratio equals 1, which defines the line between N-rich and Sc-rich growth. Under N-rich conditions, the growth is epitaxial, and the surface morphology is characterized by a densely packed array of square-shaped plateaus and four-faced pyramids with the terraces between steps being atomically smooth. The films are stoichiometric and transparent with a direct optical transition at 2.15 eV. Under Sc-rich conditions, the growth is also epitaxial, but the morphology is dominated by spiral growth mounds. The morphology change is consistent with increased surface diffusion due to a Sc-rich surface. Excess Sc leads to understoichiometric layers with N vacancies which act as donors. The increased carrier density results in an optical reflection edge at 1 eV, absorption below the 2.15 eV band gap, and a drop in electrical resistivity. {copyright} 2001 American Institute of Physics.
ISSN 00218979
Educational Use Research
Learning Resource Type Article
Publisher Date 2001-08-15
Publisher Place United States
Journal Journal of Applied Physics
Volume Number 90
Issue Number 4


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