Pore- and delamination-induced mismatch strain relaxation and conditions for the formation of dislocations, cracks, and buckles in the epitaxial AlN(0001)/SiC/Si(111) heterostructure

A method has been proposed using the example of an AlN/SiC/Si heterostructure according to which the strain state induced in multilayer epitaxial films by the mismatch in the lattice parameters and thermal expansion coefficients of the crystals can be calculated from the experimental temperature dependence of the curvature of the crystal plate. The method makes it possible to estimate the imperfection of the hetero-structure from defect-relieved mechanical stresses caused by mismatch strains. It has been found that there are specific features in the formation of the relief of AlN films grown on SiC/Si substrates prepared by the atomic substitution. Criteria for the formation and preferred orientations of defects (dislocations, cracks, delaminations, and buckles) in AlN films have been calculated. For this purpose, the surface energies and energies of adhesion for different twins at the semiconductor interfaces have been calculated using computational quantum chemistry methods for different crystal faces.