Low-pressure chemical vapour deposition of diamond films in a radio-frequency-plasma-assisted hot-filament reactor

Diamond films have been deposited using a chemical-vapour-deposition (CVD) technique involving a hybridization of the hot filament and the capacitively coupled radio-frequency (r.f) plasma at a reactor pressure of less than 2 Torr. The changes produced in surface morphology and Raman spectra of these films are investigated as a function of the magnitude of r.f, power and the concentration of methane in hydrogen. The plasma excited by low levels of r.f, power was observed to improve the overall growth rate, whereas the medium level of r.f. power improved the quality. High levels of r.f. power, however, did not yield any deposition. The growth mechanism is suggested to involve an atomic H-induced etching process along with self-bias-induced energetic electron or ion bombardment of the growing film surface when different electrode geometries were used. (C) 1998 Elsevier Science S.A. All rights reserved.