Surface structure on Ar+-ion irradiated graphite by scanning probe microscopy

The surface structure of a highly oriented pyrolytic graphite (HOPG), irrad iated by Ar+ ions with an ion energy of 0,5-1.0keV at doses below 5 x 10(11 ) ions/cm(2) during annealing, was characterized by scanning probe microsco py. The ion-induced hillocks were observed by both scanning tunneling micro scopy (STM) and atomic force microscopy (AFM) after the ion irradiation, th e heights of which, measured by STM, were larger than that measured by AFM in the tapping mode. The hillocks were recovered distinguishably by anneali ng above 470 K. Almost 85% of the hillocks disappeared after annealing at 1 270 K and they disappeared completely after annealing above 1770 K. The beh avior of defects produced by ion-irradiation in HOPG during annealing is di scussed.