MOLECULAR-BEAM EPITAXY OF PSEUDOMORPHIC SILICON/CARBON SUPERLATTICES ON SILICON SUBSTRATES

We describe the molecular beam epitaxy growth of superlattices where silicon layers with a thickness between 3 and 10 nm alternate with very thin carbon layers. High resolution x-ray diffraction reveals that the superlattices are of excellent crystalline quality and are pseudomorphic with respect to the silicon substrate. From a dynamical simulation of the diffraction spectra we conclude that the nominal carbon layers an in fact silicon-carbon alloys with a carbon content up to 50%. Given the large lattice mismatch of more than 10% of such an alloy to the silicon substrate, astonishingly thick superlattices with up to 100 periods can be grown without lattice relaxation. (C) 1995 American Institute of Physics.