MECHANICAL-PROPERTIES OF AMORPHOUS AND POLYCRYSTALLINE MULTILAYER SYSTEMS

Amorphous and polycrystalline multilayer structures containing materials with metallic (Cr, Cr3C2), ionic (Al2O3) and covalent (SiC) bonding have been prepared by magnetron sputtering and ion plating in a dual-source apparatus. Up to 1000 layers have been deposited with a constant total thickness of 2.3 mum. Below a single-layer thickness of 10-30 nm the mechanical properties stress and hardness show strong variations. On one hand it is possible that below a certain thickness the mechanical properties of a single layer change (A. Pan and J. E. Greene, Thin Solid Films, 78 (1981) 25-34). On the other hand electrical resistance and electron spin density measurements indicate that electronic effects may be involved. An attempt is made to explain the observed correlations by transport mechanisms of the electrons, by saturation of dangling bonds with delocalized electrons and by changes in the electronic band structure.