Size effect of the silicon carbide Young's modulus

A self-consistent method is used for the determination of the residual stress and the effective Young's modulus of thin 3C-SiC(111) grown on Si(111), and 3C-SiC(100) grown on Si(100). The developed method allows for the accurate determination of the stress and mechanical properties in a wide range of residual stress, only by a set of cantilevers and doubly clamped beams. The resulting thickness dependence of the effective Young's modulus is investigated and compared with different elasticity and surface relaxation models which are analysed in terms of validity in the ultrathin regime. It is shown that the decrease of the effective Young's modulus for SiC can approximately be described by surface relaxation. Other effects like the surface coverage with oxides or other phases can be neglected. Array of doubly clamped 3C-SiC(100) beams from 250 μm length down to 10 μm. The layer thickness is 43 nm.