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 process 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 thermalization of the Pt particles impinging on the substrate, and the subsequent generation of a high density of nucleation centers as well as an increase in the effective surface temperature. Despite the fact that the MgO lattice parameter is 7.4% larger than that of Pt, this higher particle energy distribution leads to a stronger film-substrate interaction and therefore to an unrelaxed, in-plane compressive strained growth. Distinct release of this compressive strain depending on growth temperature and crystalline orientation produces strong changes in the morphology of the films, leading to a 2D-3D transition for the (1 1 0) structures grown between 600 and 700 degrees C. (C) 1998 Elsevier Science B.V. All rights reserved.