engleski

Implantation conditions for diamond nanocrystals formation in amorphous silica

We present a study of carbon ion-implantation in amorphous silica, which followed by annealing in a hydrogen-rich environment leads to the preferential formation of carbon nanocrystals with cubic diamond (c-diamond), face centered cubic (n-diamond) or simple cubic ( i-carbon) carbon crystal lattices. Two different annealing treatments are applied: furnace annealing for one hour and short-lasting rapid thermal annealing, which also enables monitoring the early nucleation stage. The influences of the implanted dose and the type of annealing on carbon and hydrogen concentrations, clustering and bonding are investigated. For that purpose, a wide range of experimental techniques are applied: Rutherford backscattering, elastic recoil detection analysis, infrared spectroscopy, transmission electron microscopy, selected area electron diffraction, UV-visible absorption measurements and Raman spectroscopy. The present results, combined with the results of previous investigations of similar systems, shows that the preferential formation of the different carbon phases (diamond, n-diamond or i-carbon) depends on the implantation energy and/or the implantation dose, as well as on the annealing conditions. The diamond nanocrystals form at relatively low carbon volume density, which is achieved either by deeper implantation and/or lower implanted dose. Higher volume densities lead to the formation of n-diamond and finally to i-carbon crystal formation. The observed behavior is found to be damage related. Significant differences in optical properties of nanocrystals with different carbon phases are observed.

diamond; nanodiamond; carbon nanocrystals

nije evidentirano