Simulation of electron channelling patterns for in situ polytype analysis of silicon carbide films

For the controlled growth of hexagonal or cubic silicon carbide (SiC) polytypes, an in situ surface analysis technique is needed which is sensitive to the crystal structure of thin films whose thicknesses are in the range of a few nanometers. Diffraction effects of electrons having kinetic energies of a few keV serve this purpose very well. X-ray photoelectron diffraction patterns and electron channelling patterns (ECP) have been proven to be useful techniques for polytype differentiation. We show that the polytype specific effects in zone axis ECP of SiC polytypes can be simulated using a Bloch wave approach. Dynamical diffraction leads to characteristic patterns which show a variety of energy dependent structures. The specific zone axis patterns are caused by many-beam effects of higher order Laue zone reflections which are strongly energy dependent. We show results for 3C, 4H and 6H SiC.