Correlation of nanoindentation-induced deformation microstructures in diamondlike carbon coatings on silicon substrates with simulation studies

Abstract

The effect of the presence of diamondlike carbon coatings deposited on (100) Si substrates on the deformation mechanisms operating in the silicon substrate during contact loading have been investigated by both cross-sectional transmission electron microscopy and modeling of the stresses generated beneath the indenter tip. The observed subsurface microstructures were correlated to the Tresca shear stress and the hydrostatic stress generated in the silicon substrate beneath the indenter tip. The presence of the coating altered the stresses generated in the substrate, and changed the deformation mechanism from one of principally phase transformation in uncoated Si to predominantly dislocation motion in the silicon substrate for the diamondlike C-Si system. The magnitude and distribution of the shear and hydrostatic stresses in the substrate were found to depend on both the indentation load and the thickness of the coating. Furthermore, the observed width of deformation, parallel to the interface, which was found to increase with coating thickness, was correlated to the wider distribution of the Tresca shear stress in the substrate brought about by the presence of the coating.

The mechanical properties of energetically deposited non-crystalline carbon thin films

“…Films with thicknesses between 100 and 150 nm were deposited onto n-type conductive 6H-SiC and Si substrates. Previous nanoindentation experiments performed on carbon films supported by Si revealed that the Si deformed significantly under moderate loads [18]. 6H-SiC was chosen here as a precautionary measure due to its relatively high elastic constant (400 GPa) and because no phase changes occur during indentation (unlike in Si [19]).…”