NEW CARBON NITRIDE PHASE BY HIGH-DOSE N ION-IMPLANTATION IN GLASSY-CARBON

The possibility for the synthesis of CN compounds by high-dose N impla ntation of glassy carbon is investigated. The changes in volume and su rface morphology and the retained N concentration as a function of ion dose are reported. For both N and C (used as a control), implantation initially induces compaction in the surface region that saturates at a density above 2.6 g/cm(3). After formation of this dense surface lay er, additional implantation causes the material to expand to accommoda te the implanted ions and vacancies formed during the implantation pro cess. For N the swelling is initially linear in fluence up to 5X10(17) /cm(2) with a volume increase of 16 Angstrom(3) per added id atom; thi s is twice the volume per atom in the compacted substrate. Above a dos e of 5X10(17) N/cm(2) the swelling behavior is more complex. A phase c hange is observed to occur at a dose between 5X10(17) and 1X10(18)/cm( 2) which is concomitant with at least some of the implanted N being dr iven to the surface. In addition, micron-sized surface features are se en by scanning electron microscopy, and a significant surface rougheni ng occurs. Ion backscattering spectra have been used to characterize t he implanted N profile. The maximum retained concentration was found t o be 30 at. %. (C) 1995 American Institute of Physics.