Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/59184
Type: Artigo
Title: Pd growth on Cu(111): stress relaxation through surface alloying?
Author: Paniago, R.
Siervo, A. de
Soares, E. A.
Pfannes, H.-D.
Landers, R.
Abstract: On the basis of a high-precision reflection high-energy electron diffraction (RHEED) investigation details of the growth of Pd on a Cu(1 1 1) single crystal substrate at room temperature are reported. Because of the +7.6% misfit of the Pd lattice spacing as compared to Cu, perfect pseudomorphous growth would result in highly stressed ultra-thin films. RHEED analysis shows that as a function of Pd coverage initially the film starts to grow with the in-plane Cu(1 1 1) lattice parameter. With increasing coverage the lattice parameter rapidly changes to the ''natural'' lateral lattice parameter of Pd(1 1 1). We propose that a progressive increase of the equilibrium lateral lattice parameter by alloying (Vegards law) releases the stress in the Pd/Cu(1 1 1) system. With a coverage of n > 2 ML (n = number of monolayers, ML) pure Pd layers are formed, since the in-plane lattice parameter equals the expected value for Pd at n = 2 ML. Our conclusion that Pd-Cu surface alloying acts as a relaxation mechanism in this quasi-pseudomorphous growth system, corroborates scanning tunneling microscopy [Surf. Sci. 408 (1998) 43] which also suggests formation of a random surface alloy in the earlier stages of Pd growth on Cu(1 1 1).
On the basis of a high-precision reflection high-energy electron diffraction (RHEED) investigation details of the growth of Pd on a Cu(1 1 1) single crystal substrate at room temperature are reported. Because of the +7.6% misfit of the Pd lattice spacing as compared to Cu, perfect pseudomorphous growth would result in highly stressed ultra-thin films. RHEED analysis shows that as a function of Pd coverage initially the film starts to grow with the in-plane Cu(1 1 1) lattice parameter. With increasing coverage the lattice parameter rapidly changes to the ‘‘natural’’ lateral lattice parameter of Pd(1 1 1). We propose that a progressive increase of the equilibrium lateral lattice parameter by alloying (Vegards law) releases the stress in the Pd/Cu(1 1 1) system. With a coverage of n > 2 ML (n = number of monolayers, ML) pure Pd layers are formed, since the in-plane lattice parameter equals the expected value for Pd at n = 2 ML. Our conclusion that Pd–Cu surface alloying acts as a relaxation mechanism in this quasi-pseudomorphous growth system, corroborates scanning tunneling microscopy [Surf. Sci. 408 (1998) 43] which also suggests formation of a random surface alloy in the earlier stages of Pd growth on Cu(1 1 1).
Subject: Cobre
Paládio
Epitaxia por feixe molecular
Elétrons - Difração
Ligas (Metalurgia)
Country: Holanda
Editor: Elsevier
Citation: Surface Science. Elsevier Science Bv, v. 560, n. 41699, n. 27, n. 34, 2004.
Rights: fechado
Identifier DOI: 10.1016/j.susc.2004.05.047
Address: https://www.sciencedirect.com/science/article/pii/S0039602804005400
Date Issue: 2004
Appears in Collections:IFGW - Artigos e Outros Documentos

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