PREPARATION AND PROPERTIES OF HIGHLY TETRAHEDRAL HYDROGENATED AMORPHOUS-CARBON

A highly tetrahedrally bonded, hydrogenated amorphous carbon (ta-C:H) has been deposited from an acetylene-fed plasma beam source. The plasm a beam source is operated to provide a highly ionized, monoenergetic p lasma beam of C2H2+ ions. The resulting films are: characterized in te rms of their sp(3) content, mass density, intrinsic stress, surface ro ughness, radial distribution function, C-H bonding, Raman spectra, opt ical gap, electrical conductivity, gap states, Youngs modulus, and har dness. The sp(3) content reaches a maximum value of 75% at an ion ener gy of 200 eV, or 92 eV per C ion. The density and stress also reach a maximum at this ion energy. The formation of ta-C:H is interpreted in terms of the subplantation of C+ ions, which produces a densified, sp( 3) bonded network. The C-H vibration spectra suggest that C sp(2) site s form C=C alkene groups. The optical gap E(04) reaches a maximum of 2 .85 eV and increases with the sp(3) fraction. The spin density due to defects is high and decreases with increasing ion energy. The Youngs m odulus and hardness measured by microindenter reach maximum values of 290 and 61 GPa, consistent with the highly sp(3) bonding. The variatio n of hardness with sp(3) fraction is consistent with the constraint mo del of network rigidity.