Focused ion beam irradiation of ZnO film: an atomic force microscopy study

The evolution of surface morphology on ZnO film has been investigated as a function of ion sputtering time and incidence angles using atomic force microscopy at room temperature. Ripples were found to form at 45 degrees and 60 degrees incidence angles with orientation perpendicular to the projected ion beam direction. The ripple wavelength grows logarithmically with the sputtering time. The surface roughness initially grows exponentially and then asymptotically approaches a saturation value. The results might be explained by the interplay between the Bradley-Harper model-dependent ripple orientation and diffusion determined scaling laws.