Effect of crystal anisotropy and adhesive forces on laser induced deformation patterns in covalently bonded thin films

The effect of crystal structure on laser induced deformation patterns in thin films and surfaces is analyzed within the framework of a dynamical model for the coupled evolution of defect densities and deformation fields. In crystals with covalent bonding, such as Si and SiC, preferential bond breaking may occur, as a result of the relative orientation of the laser electric field and crystallographic axes. We extend here our theoretical framework to incorporate the effects of anisotropic defect diffusion, and the influence of film-substrate adhesion on deformation pattern selection and stability of thin films subjected to laser beams. We also compare theoretical predictions to experimental observations on single crystal silicon wafer surfaces. Furthermore, it is predicted that the laser induced damage threshold for SiC single crystals can be in excess of 200 J/cm2