Growth of fcc Co in sputter-deposited Co/Au multilayers with (1 1 1) texture

Abstract

The growth of Co/Au multilayers on Si(0 0 1)/SiN x is investigated by means of transmission and high resolution electron microscopy (TEM-HREM) as a function of Co layer thickness. Although there is an amorphous SiN x buffer layer between the substrate and the multilayer, the growth of alternative Co and Au layers exhibit strong texture with the (1 1 1) planes of Au oriented normal to the growth direction. The multilayer consists of columns that are composed of small misoriented crystals and multiple twins having as twin planes the (1 1 1) planes of growth. Electron diffraction analysis shows that when the Co layers are thinner than the Au layers an average face centred cubic (fcc) lattice is formed throughout the columnar structure of the multilayer, adopting an interplanar d-spacing of 0.229 nm along the growth direction. When the Co layer thicknesses become equal or greater than Au thickness then two separate cubic lattices appear due to internal stress relaxation.