Orientation selection and microstructural evolution of epitaxial platinum films on (001) magnesium oxide

摘要

Thin platinum films were deposited at several different deposition rates and with varying thickness on (001)-cut MgO single crystal substrates by electron beam evaporation. A mixture of two epitaxial Pt orientations were detected in the films by X-ray diffraction and planar ion channeling experiments: (001)(100)Pt // (001)(100)MgO (the cube-on-cube orientation) and (111)(110)Pt // (001)(110)MgO. The effect of deposition rate on film orientation indicated the (111)Pt orientation was preferred under conditions of high driving force for nucleation. The volume fraction of the films occupied by the (111) orientation increased with nominal film thickness, at a constant substrate temperature and deposition rate. This result indicates crystallites having the (111)Pt orientation grew more quickly following nucleation than the (001). The mosaic spread of the Pt orientation decreased markedly as the nominal film thickness increased from approximately 1.5 nm (isolated islands) to 20 nm (continuous film).