Suppression of phase separation in InGaN due to elastic strain
S. Yu. Karpov
Advanced Technology Center
This article was received on Thursday, June 18, 1998 and
accepted on Thursday, September 10, 1998. Abstract
The effect
of elastic strain in epitaxial InGaN layers coherently grown on GaN
wafers on spinodal decomposition of the ternary compound is examined. The effect
results in considerable suppression of phase separation in the strained InGaN
layers. To predict correctly the position of the miscibility gap in the T-x diagram
it is important to take into account the compositional dependence of the
elastic constants of the ternary compound. The contribution of the elastic strain to
the Gibbs free energy of InGaN is calculated assuming uniform compression of
the epitaxial layer with respect to the underlying GaN wafer. The interaction of binary
constituents in the solid phase is accounted for on the base of regular
solution model. The enthalpy of mixing is estimated using the Valence Force
Field approximation. The strain effect becomes stronger with increasing In
content in the InGaN. As a result the miscibility gap shifts remarkably into
the area of higher InN concentration and becomes of asymmetrical shape. Various
growth surface orientations and the type of crystalline structure (wurtzite or
sphalerite) provide different effects of the elastic strain on phase separation
in ternary compounds. Outline
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Cite this article as: MRS Internet J. Nitride Semicond. Res. 3, 16(1998).
last updated Thursday, September 10, 1998 1:10:37 PM.© 1998 The Materials Research Society
