Raman spectroscopy was used to investigate the effects of dynamic and post-implantation annealing upon glassy C which had been implanted with 50keV C ions to a dose of 5 x 1016/cm2. The post-implantation annealing of damage in the ion-modified material was found to occur in 2 stages. These stages were between 500 and 800K, and above 1300K, and corresponded to the thermal energy which was required to activate C interstitials and vacancies, respectively. When mobilized, these defects diffused through the implanted layer and reduced the bond-angle disorder. This then led to an increase in order as interstitial-vacancy recombination occurred. The effects of ion-beam irradiation upon the final structure of glassy C were found to be a sensitive function of the sample temperature during irradiation. This dependence was explained in terms of dynamic annealing and radiation-enhanced diffusion. It was found that 3 temperature regimes were important. At irradiation temperatures of less than 300K, defect motion during irradiation was suppressed. At irradiation temperatures of between 300 and 600K, the mobility of C interstitials during irradiation resulted in dynamic annealing, and thereby prevented amorphization. Thus, ion irradiation created a highly disordered but essentially graphitically bonded material. At irradiation temperatures above 600K, the vacancy mobilities were sufficiently high for most ion-induced defects to be dynamically annealed. At irradiation temperatures above 800K, the unimplanted glassy C microstructure was retained after ion irradiation. The activation energies for interstitial and vacancy mobility compared well with those found in other forms of C.

D.G.McCulloch, S.Prawer: Journal of Applied Physics, 1995, 78[5], 3040-7