TEXTURED STRUCTURE OF DIAMOND-LIKE CARBON PREPARED WITHOUT HYDROGEN

Layers of diamond-like material can be grown in a ultrahigh vacuum environment free from hydrogen with a laser plasma source. Substrates require no special preparation or seeding and materials including silicon, fused silica, glass, gold, copper, germanium, InP, ZnS, and polycarbonate and polyimide plastics are readily coated. Generally, our films resemble materials first quenched from ion beams at very slow deposition rates. Although a crystalline structure had been previously inferred, the data were not compelling and this material is generally viewed as a dehydrogenated version of amorphous diamond-like carbon. The purpose of this report is to communicate strong evidence that our diamond-like material prepared with a laser plasma source in the absence of hydrogen is composed of tightly packed diamond clusters. Extensive examinations of a variety of films with scanning tunneling and scanning electron microscopies show the clear prevalence of the structure recently predicted by Angus in which sp3 clusters are bounded together with other carbon polytypes. Grain size is about 1000 angstrom and the diamond character is attested by the agreement of morphology, density, optical properties and soft X-ray spectroscopy. Measurements agree on supporting a fraction of about 75% diamond bonding.