Submicron-scale surface roughening induced by ion bombardment

The scanning tunneling microscope (STM) was used to quantitatively investigate nonequilibrium surfaces of graphite roughened by sputter etching with 5-keV Ar ions. The resulting surface morphology depended strongly on the ion flux and fluence, as well as the sample temperature. The height-correlation functions of the roughened surfaces were calculated directly from the STM topographs and compared to linear-response theory and scaling analyses for the propagation of growing fronts. The surfaces developed correlated structures characterized by a length that diverged with increasing ion fluence