Growth of thin Co films on W(1 1 0) and Au(1 1 1) layers prepared on Al2O3(1 1 2̄ 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 Al2O3(1 1 2̄ 0) substrates and investigated by means of low energy electron diffraction and Auger electron spectroscopy. The growth of W on Al2O3(1 1 2̄ 0) was found to depend strongly on substrate temperature and film thickness. W films deposited at a substrate temperature Tp=1200 K with a film thickness dW⩾100 Å revealed a bcc(1 1 0) structure with a mean terrace size of 40 Å. Epitaxial growth of Au was achieved at Tp=300 K with a layer thickness dAu=30 Å for a deposition onto the W(1 1 0) substrate layers. The structural properties of thin Co films grown at Tp=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.