DC-ARC PLASMA DEPOSITION OF SMOOTH NANOCRYSTALLINE DIAMOND FILMS

We report on chemical vapour deposition growth of nanocrystalline (gra in size 30-50 nm) diamond films of 100 nm to 2 mu m thickness in metha ne-rich mixtures. A d.c. are discharge in CH4-H-2-Ar gas mixtures with a methane percentage CH4/(CH4 + H-2) varied from 10% to 100% was used for diamond deposition on Si substrates seeded with ultrafine (5 nm) diamond particles. The films obtained were characterized by scanning e lectron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray e xcited Auger electron spectroscopy. Remarkably well-crystallized diamo nd films were produced even in hydrogen-free gas mixtures. Raman spect ra confirmed the nanocrystalline structure of all the films examined. The him hardness measured with a nanoindenter was in the range 70-85 G Pa typical for diamond, the highest values corresponding to 100% metha ne content. The films were very smooth with surface roughness R(a)<20 nm. The essential improvement in surface smoothness was obtained by me ans of laser-induced disintegration of coalesced seeding particles.