Effect of epitaxial strain on phase separation in thin films

Lahiri, Arka and Abinandanan, TA and Gururajan, MP and Bhattacharyya, Saswata (2014) Effect of epitaxial strain on phase separation in thin films. In: PHILOSOPHICAL MAGAZINE LETTERS, 94 (11). pp. 702-707.

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Abstract

In epitaxially grown alloy thin films, spinodal decomposition may be promoted or suppressed depending on the sign of the epitaxial strain. We study this asymmetry by extending Cahn's linear theory of spinodal decomposition to systems with a composition dependent lattice parameter and modulus (represented by Vegard's law coefficients, GRAPHICS] and y, respectively), and an imposed (epitaxial) strain (e). We show analytically (and confirm using simulations) that the asymmetric effect of epitaxial strains arises only in elastically inhomogeneous systems. Specifically, we find good agreement between analytical and simulation results for the wave number GRAPHICS] of the fastest growing composition fluctuation. The asymmetric effect due to epitaxial strain also extends to microstructure formation: our simulations show islands of elastically softer (harder) phase with (without) a favourable imposed strain. We discuss the implications of these results to GeSi thin films on Si and Ge substrates, as well as InGaAs films on GaAs substrates.

Item Type:	Journal Article
Publication:	PHILOSOPHICAL MAGAZINE LETTERS
Additional Information:	Copy right for this article belongs to the TAYLOR & FRANCIS LTD, 4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLAND
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	13 Jan 2015 04:46
Last Modified:	13 Jan 2015 04:46
URI:	http://eprints.iisc.ac.in/id/eprint/50637

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