Growth of thin Co films on W(110) and Au(110) layers prepared on Al2O3(11(2)over-bar-0)

Thin epitaxial W(1 1 0)/Co and Au(1 1 1)/Co films were prepared by molecular beam epitaxy on single crystal sapphire Al-2,O-3 (1 1 (2) over bar 0) substrates and investigated by means of low energy electron diffraction and Auger electron spectroscopy. The growth of W on Al2O3(1 1 (2) over bar 0) was found to depend strongly on substrate temperature and film thickness. W films deposited at a substrate temperature T-p = 1200 K with a film thickness d(W) greater than or equal to 100 Angstrom revealed a bcc(1 1 0) structure with a mean terrace size of 40 Angstrom Epitaxial growth of An was achieved at T-p = 300 K with a layer thickness d(Au) = 30 Angstrom for a deposition onto the W(1 1 0) substrate layers. The structural properties of thin Co films grown at T-p = 300 K on the W(1 1 0) and Au(1 1 1) substrate layers were studied as a function of Co film thickness for wedge-shaped layers. The Co films were found to grow epitaxially in both cases with distinct growth modes and lattice strains. (C) 2001 Elsevier Science B.V. All rights reserved.