Structure and thermal stability of sputtered metal/oxide multilayers: The case of Co/Al2O3

摘要: Co/Al2O3 multilayers have been grown on sapphire (1120) substrates by rf sputtering techniques. In situ resistance measurements reveal percolation thresholds of Co between 1.5 and 2.5 nm. Continuous metallic layers appear at thicknesses beyond 3.0 grow in a polycrystalline manner, whereas Al2O3 are amorphous, as inferred from x‐ray transmission electron microscope studies. By fitting reflectivity data, interface roughnesses only 0.25 nm were obtained. Annealing experiments up to 800 °C show gradual internal oxidation the interface, while overall structure multilayer period remain stable with constant values. At 900 °C layered is partly destroyed forms crystallites thicker than one former layer.