FORMATION OF DEFECT CLUSTERS IN ELECTRON-IRRADIATED DIAMOND AT 16-K AND 87-K

A type IIa natural diamond was irradiated with 300 kV electrons at 16 and 87 K. Transmission electron microscopy and electron energy-loss spectroscopy were employed to investigate the phase stability of diamond under electron irradiation. At both temperatures, the diamond structure was found to be stable, and the formation of defect clusters was observed. The present results in comparison to previous work on ion implantation indicate that displacement cascade damage is a prerequisite for irradiation-induced phase transformation from diamond to amorphous r-arbon or graphite. The temperature dependence of the cluster size suggests that interstitials are thermally mobile above 50 K.