Premium
Theory of the Anomalous Low Band‐Gap Pressure Coefficients of Semiconductor Strained Layers
Author(s) -
Downes J.R.,
van Uden N.W.A.,
Bosher S.H.B.,
Frogley M.D.,
Dunstan D.J.
Publication year - 2001
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(200101)223:1<205::aid-pssb205>3.0.co;2-e
Subject(s) - ternary operation , poisson distribution , elasticity (physics) , materials science , poisson's ratio , semiconductor , condensed matter physics , band gap , lattice (music) , binary number , thermodynamics , equation of state , statistical physics , mathematics , physics , statistics , optoelectronics , arithmetic , computer science , acoustics , programming language
There is a significant and unexplained drop in the band‐gap pressure coefficients of III–V ternary semiconductor alloys grown as strained layers compared with the bulk binary values. For example, the drop for In x Ga 1— x As is about (50 x) meV/GPa. In the past, first order effects of pressure have been treated using linear elasticity and this fails to predict the observed pressure coefficients. Ideally strained layers would be treated using an equation of state valid for an arbitrary state of strain, however, such theory is not currently available. Here, we present work towards such an equation and an approximate analysis using non‐linear elasticity theory that does account for the data observed. The analysis relies on treating the non‐linear variation of the substrate and layer lattice constants and the variation of the Poisson's ratio with respect to pressure. The analysis is tested against experimental data for 〈001〉‐grown layers available in the literature. In addition, we present new results on layers grown in the 〈111〉 direction. This acts as a further test on the theory because it involves a different Poisson's ratio. The experimental results agree well with the predictions of the non‐linear theory.