Lateral templating of self-organized ripple morphologies during focused ion beam milling of Ge

We report the use of the boundary between ion irradiated and unirradiated regions to template the lateral self-organization of nanoscale ripplelike morphological features that spontaneously evolve during uniform ion irradiation. Using uniform rastering of a 30 keV Ga + focused ion beam, up to eight periods of ripples have been templated to follow the boundary under the set of conditions explored. We report the dependence of the range of lateral templating on incident angle, ion dose, and boundary inclination with respect to the projected ion beam direction. We show that the ripple organization is influenced by a down-step as well as by an up-step in the surface morphology.