Epitaxial growth of Cu(100) and Pt(100) thin films on perovskite substrates

Pulsed laser deposition has been used to grow epitaxially oriented thin films of Cu and Pt on (100)-oriented SrTiO₃ and LaAlO₃ substrates. X-ray diffraction results illustrated that purely epitaxial Cu(100) films could be obtained at temperatures as low as 100 °C on SrTiO₃ and 300 °C on LaAlO₃. In contrast, epitaxial (100)-oriented Pt films were attained on LaAlO₃(100) only when deposited at 600 °C. Atomic force microscopy images showed that films deposited at higher temperatures consisted of 3D islands and that flat, layered films were obtained at the lowest deposition temperatures. Importantly, Cu films deposited at 100 °C on SrTiO₃(100) were both purely (100)-oriented and morphologically flat. Pt and Cu films displaying both epitaxial growth and smooth surfaces could be obtained on LaAlO₃(100) only by using a three-step deposition process. High-resolution transmission electron microscopy demonstrated an atomically sharp Cu/SrTiO₃ interface. The crystalline and morphological features of Cu and Pt films are interpreted in terms of the thermodynamic and kinetic properties of these metals.