Cone formation as a result of whisker growth on ion bombarded metal surfaces

We were able to show experimentally that the seed metals which can cause cone development on ion bombarded metal targets need not to have a lower sputtering yield as widely believed but rather a higher melting point. By lowering the bombarding ion energy to near sputtering threshold values (<100 eV) one observes the growth of genuine single crystal whiskers which point in all directions not related to the direction of ion incidence. We are now convinced that (intentional or unintentional) seed cones are the result of an interplay among whisker growth, surface movement of atoms, and the effects of sputtering.