Compositional variation of AlGaN epitaxial films on 6H-SiC substrates determined by cathodoluminescence.
A. Petersson
Division of Solid State Physics, Lund University, Box 118, S-221 00 Lund, Sweden
and
Crystal Fibre A/S, Blokken 84, DK-3460 Birkerød, Denmark
Anders Gustafsson , L. Samuelson
Division of Solid State Physics, Lund University, Box 118, S-221 00 Lund, Sweden
Satoru Tanaka
Research Institute for Electronic Science, Hokkaido University, Kita, 12-Nishi 6, Kita-ku, Sapporo 060-0812 Japan
Yoshinobu Aoyagi
The Institute of Physical and Chemical Research (RIKEN)
This article was received on Friday, May 3, 2002 and
accepted on Thursday, June 27, 2002. Abstract
High
quality epitaxial films of AlxGa1-xN, grown on SiC
substrates, were investigated using spatially resolved cathodoluminescence
(CL), scanning electron microscopy, and atomic force microscopy. A variation in
the observed peak energy position of the CL was related to alloy fluctuations.
CL was used to reveal relative alloy fluctuations of approximately 1% on a
sub-micrometer scale, with a precision difficult to surpass with other
available techniques. By correlating data from the different techniques, a
model was derived. The main feature of it is an alloy fluctuation on the
micrometer scale, seeded during the initial growth and extending through the
epitaxial film. These alloy fluctuations seems to be related to terrace steps
(
5 nm in height), formed preferentially at scratches on the SiC
surface. This investigation indicates that the initial growth of epitaxial
films is critical and structures formed at the beginning of the growth tend to
persist throughout the growth. Further, a strain gradient from the SiC
interface extending towards the surface, was observed.Outline
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Cite this article as: MRS Internet J. Nitride Semicond. Res. 7, 5(2002).
last updated Monday, July 1, 2002 4:30:43 PM.© 2002 The Materials Research Society
