Growth temperature and relaxation of lattice strain in epitaxial Pt films exhibiting diffraction fringes

We fabricated Pt epitaxial films on SrTiO₃(111) using a dc-sputtering method. The surface structure, the surface morphology, and the electrochemical properties are discussed. Reflection high-energy electron diffraction (RHEED) observation reveals that epitaxial films are obtained at substrate temperatures higher than 450 °C. The RHEED patterns exhibit clear streaks up to the 1st order Laue zone, which indicates the high crystallinity and the atomically smooth surface. Oscillation in the intensity of the X-ray diffraction pattern is observed near the Pt-111 peak. It is caused by multiple scattering, showing the perfection in the lattice plane stacking along the out-of-plane direction. Analysis using a dynamic theory of diffraction shows that the film is subjected to a compressive in-plane lattice strain. The in-plane lattice parameter decreases by approximately 0.3%. The oscillation amplitude decreases at 600 °C, which suggests that the lattice relaxation occurs caused by misfit dislocation.