EPITAXY, STRAIN AND MORPHOLOGY OF LOW AR PRESSURE SPUTTERED PT THIN-FILMS

We show that the use of low Ar pressures in the sputter deposition pro cess leads to the growth of epitaxial Pt thin films on MgO(1 0 0) and (1 1 0) at moderate temperatures. This is due to the low thermalizatio n of the Pt particles impinging on the substrate, and the subsequent g eneration of a high density of nucleation centers as well as an increa se in the effective surface temperature. Despite the fact that the MgO lattice parameter is 7.4% larger than that of Pt, this higher particl e energy distribution leads to a stronger film-substrate interaction a nd therefore to an unrelaxed, in-plane compressive strained growth. Di stinct release of this compressive strain depending on growth temperat ure and crystalline orientation produces strong changes in the morphol ogy of the films, leading to a 2D-3D transition for the (1 1 0) struct ures grown between 600 and 700 degrees C. (C) 1998 Elsevier Science B. V. All rights reserved.