EPITAXIAL-GROWTH OF CO CU [100] AND [111] SUPERLATTICES VIA RF-SPUTTERING ON SAPPHIRE (11(2)OVER-BAR0)-SUBSTRATES/

Co/Cu superlattices with total thicknesses ranging from 10 nm to 60 nm and with periodicities of 1.6-8.5 nm were sputtered on single-crystal line sapphire (1120BAR)-substrates. Sputtering with low rates at room temperature yields samples of high epitaxial and crystalline quality. By careful choice of the sputtering parameters, either the fcc [100] o r the fcc [111] orientation can be selected as growth direction on one and the same substrate orientation. The preference for a particular f ilm orientation appears to be kinetically driven. In all cases, the av erage lattice spacings dBAR and the appearance of satellite reflection s in x-ray Bragg-scans point to coherent growth up to thicknesses of 3 0 nm. X-ray small angle reflectivity measurements reveal clear oscilla tions and satellites indicative for smooth interfaces. Scanning electr on microscope (SEM) and transmission electron microscope (TEM) observa tions supplement the characterization of the films.