PULSED-LASER DEPOSITION OF CARBON-FILMS - DEPENDENCE OF FILM PROPERTIES ON LASER WAVELENGTH

We have grown thin carbon films by pulsed laser deposition and have in vestigated the extent to which the properties of such films, as well a s the processes responsible for these properties, are laser wavelength dependent. Films were grown by ablating material from a graphite targ et onto room temperature Si(100) substrates with 1064 and 248 nm laser radiation. The films were analyzed by in situ electron energy loss sp ectroscopy and by ex situ Raman spectroscopy. The results indicated th at films grown with 1064 nm ablation were graphitic, while those grown with 248 nm radiation were diamond-like. We have also examined the ma ss and kinetic energy distributions of the particles ejected from grap hite by the two laser wavelengths. The results indicated that irradiat ion of graphite with 1064 nm laser radiation results in the ejection o f a series of carbon cluster ions C(n+)(1 less-than-or-equal-to n less -than-or-equal-to 30) with mean kinetic energies less than 5 eV. Ablat ion of graphite with 248 nm radiation results in the ejection of prima rily C2+ and C3+ with mean kinetic energies of 60 and 18 eV, respectiv ely. These results suggest that large, low energy clusters produce gra phitic films, while small, high energy clusters produce films of diamo nd-like carbon.