Atomic assembly of Cu/Ta multilayers: Surface roughness, grain structure, misfit dislocations, and amorphization

M. F. Francis, M. N. Neurock, X. W. Zhou, J. J. Quan, H. N G Wadley, Edmund B. Webb

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21 Scopus citations

Abstract

Molecular dynamics simulations and selected experiments have been carried out to study the growth of Cu films on (010) bcc Ta and the deposition of Cux Ta1-x alloy films on (111) fcc Cu. They indicate that fcc Cu films with a (111) texture are always formed when Cu is deposited on Ta surfaces. These films are polycrystalline even when the Ta substrate is single crystalline. The grains have one of two different orientations and are separated by either orientational or misfit dislocations. Periodic misfit dislocations and stacking faults develop within these grains to release structure difference induced misfit strain energy. The Cu film surface roughness was found to decrease with increase in the adatom energy for deposition. When Cux Ta1-x is deposited on Ta, the films always have a higher Cu composition than that of the vapor mixture. This arises from a surface segregation phenomenon. When the Cu and Ta fractions in the films are comparable, amorphous structures form. The fundamental origins for the segregation and amorphization phenomena are discussed.

Original languageEnglish (US)
Article number034310
JournalJournal of Applied Physics
Volume104
Issue number3
DOIs
StatePublished - 2008

Bibliographical note

Funding Information:
Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Co., for the United States Department of Energy’s National Nuclear Security Administration under Contract No. DEAC04-94AL85000.

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