THE RAMAN-SPECTRUM OF AMORPHOUS DIAMOND

We present the Raman spectrum of an amorphous, fully sp(3)-bonded carb on network;. The reduced Raman spectrum agrees closely with the calcul ated density oi states of diamond. The results have been obtained from nanoclusters produced deep inside a single crystal diamond irradiated with MeV He ions. The deep implantation creates amorphous sp(3) bonde d C clusters along the ion tracks, within a largely intact diamond mat rix. The matrix maintains the clusters under high pressure. preventing the relaxation to sp(3) bonded structures. Sharp peaks associated wit h defect structures unique to MeV ion implantation are observed at 142 2, 1447, 1467, 1496, 1540, 1563, 1631, 1649, 1683 and 1726 cm(-1). We also observe a shoulder in the reduced Raman spectrum at ca 1120 cm(-1 ) which we tentatively attribute to surface phonon modes. The: results provide the Raman signature that might be expected from tetrahedrally bonded amorphous carbon films with no graphite-like amorphous compone nts. (C) 1998 Elsevier Science S.A.