PRODUCTION OF BETA-SIC BUFFER LAYERS FOR CVD DIAMOND THIN-FILMS BY ION-IMPLANTATION

The difference between the lattice constants of silicon and diamond is approximately 52%. Therefore a heteroepitaxial buffer layer on the silicon substrate should improve the crystallization behaviour of diamond obtained by chemical vapour deposition (CVD). Beta-SiC has a lattice constant which is just between these two materials. A 100 keV ion implanter has been used to attempt the generation of an SiC buffer layer. C-12 ions were implanted into a silicon target at different energies (40 and 100 keV), ion doses (between 3.3 x 10(18) and 1.0 x 10(18) cm-2) and target temperatures (liquid-nitrogen temperature to 900-degrees-C). Some samples were annealed at 1200-degrees-C in an N2 atmosphere. [100]-oriented silicon as well as [111]-oriented silicon was used as target materials. A wet-etching process in a KOH solution was employed to expose the implanted beta-SiC layer. CVD diamond films were deposited on substrates which were pre-treated by these methods. Subsequent to the implantation and annealing processes the specimens were investigated by means of X-ray diffraction, Raman spectroscopy and Rutherford backscattering spectroscopy. The investigation demonstrate that, although defective, endotaxial beta-SiC layers can be formed by ion implantation of C-12 in silicon substrates.