Morphology of graphite surfaces after ion-beam erosion

A review of the topographic evolution of (0001) highly oriented pyrolytic graphite surfaces eroded by 2--50 keV ion beams and investigated using scanning tunneling microscopy is given. For tilted incidence of the ion beam and intermediate ion fluences of about 10¹⁷cm^-2, a periodic ripple topography with characteristic wavelengths between 40 and 700 nm was found. This morphology evolution is explained by a linear continuum theory of the interplay between material removal during sputtering and surface diffusion. The evolution of the surface morphology was measured as a function of the ion mass, the ion energy, and the target temperature. The validity of the linear erosion theory in the observed parameter space has been tested and its limitations for increasing fluences and ion energies and varying temperatures shown.