Effects of argon dilution of an ethanol/hydrogen gas feed on the growth ofdiamond by hot-filament chemical vapor deposition

We studied the effects on the growth kinetics and properties of diamond and carbon-like diamond films obtained by the introduction of argon at low to high concentrations (0-85 vol.% Ar) into the feed mixture (ethanol and hydr ogen) of a hot-filament chemical vapor deposition (CVD) reactor. Scanning e lectron microscopy (SEM) analysis revealed that the addition of argon induc es an increase in the diamond grain size, and increases the flaws between t he grains and the density of vacancy defects. Well-faceted diamond films of good quality (measured by Raman spectroscopy) have been obtained using up to 65 vol.% of argon in the gaseous mixture, while higher concentrations (8 5 vol.% Ar) produce diamond-like carbon or other complex carbon structures. We also observed an increase in the diamond growth rate with argon additio n that was associated with an increase in carbon free radicals (up to simil ar to 40 vol.% Ar) or to the increase in the filament temperature necessary to keep the substrate temperature constant at higher Ar concentrations (ab ove similar to 40 vol.% Ar). Room temperature photoluminescence spectroscop y also confirmed that argon addition increases the density of vacancy defec ts in the diamond structure. (C) 2000 Elsevier Science B.V. All rights rese rved.