Ripple structures on ion bombarded surfaces arising from the sputter yield dependence on incidence angle

It is shown that ripple structures on oblique incidence ion bombarded surfaces can be stable features under ion erosion without the necessity to invoke mass redistribution, surface diffusion or micro-roughening due to surface curvature dependent energy deposition. Instead the patterns are predicted to be a natural consequence of non-linear effects due to the dependence of the sputtering yield on the angle of incidence.