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Band-gap engineering in amorphous/microcrystalline ScxGa1-xN.

Published online by Cambridge University Press:  21 March 2011

M. E. Little  and
M. E. Kordesch
M. E. Little
Affiliation:
ICASE, NASA Langley Research Center Hampton, VA 23666 [email protected]
M. E. Kordesch
Affiliation:
Condensed Matter and Surface Science Program Department of Physics and Astronomy Ohio University, Athens, OH 45701
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Abstract

Reactive sputtering was used to grow thin films of ScxGa1-xN with scandium concentrations of 20%-70% on quartz substrates at temperatures of 300-675 K. X-ray diffraction (XRD) of the films showed either weak or no structure, suggesting the films are amorphous or microcrystalline. Optical absorption spectra were taken of each sample and the optical band gap was determined. The band gap varied linearly with increasing Ga concentration between 2.0 and 3.5 eV. Ellipsometry was used to confirm the band gap measurements and provide optical constants in the range 250-1200 nm. ScN and GaN have different crystal structures (rocksalt and wurzite, respectively), and thus may form a heterogeneous mixture as opposed to an alloy. Since the XRD data were inconclusive, bilayers of ScN/GaN were grown and optical absorption spectra taken. A fundamental difference in the spectra between the bilayer films and alloy films was seen, suggesting the films are alloys, not herterogeneous mixtures.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 693 , 2001 , I3.29.1
Copyright
Copyright © Materials Research Society 2002

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