A LASER RAMAN-STUDY OF D-IRRADIATED DIAMOND AND GRAPHITE( AND HE+ ION)

Type Ib diamond and highly orientated graphite were irradiated with 25 keV D+ or He+ ions at room temperature to several doses, and examined by laser Raman spectroscopy. The absolute intensity of the diamond pe ak at 1330 cm-1 gradually decreased with increasing dose, finally disa ppeared at a critical dose, and a very broad peak appeared instead, in dicating an amorphization of the diamond. Though the critical dose for D+ was larger than that for He+, the critical dpa calculated by energ y deposition for both ions was nearly the same, which means the chemic al effect of implanted species on the amorphization is negligible. Nev ertheless, a certain difference was observed in the broad Raman spectr a of the amorphized specimen between the D+ and He+ irradiation. The R aman spectrum of the D+ irradiated diamond was quite similar to that o f amorphous hydrogenated carbon (a-C:H) and a Raman component, which i s due to C-D bond formation, appeared at around 1550 cm-1 only for the D+ irradiated diamond. A similar spectrum was also seen in the amorph ized graphite by D+ irradiation. This leads us to conclude that the am orphized structures of diamond and graphite under D+ irradiation are v ery similar to that of a-C: H.