Ultrahard carbon nanocomposite films

Modest thermal annealing to 600 degrees C of diamondlike amorphous-carbon ( a-C) films grown at room temperature results in the formation of carbon nan ocomposites with hardness similar to diamond. These nanocomposite films con sist of nanometer-sized regions of high density a-C embedded in an a-C matr ix with a reduced density of 5%-10%. We report on the evolution of density and bonding topologies as a function of annealing temperature. Despite a de crease in density, film hardness actually increases similar to 15% due to t he development of the nanocomposite structure. (C) 2000 American Institute of Physics. [S0003- 6951(00)04420-X].