Five-fold twin structures in sputter-deposited nickel alloy films

Abstract

The deposition of a Ni-1at. % P film resulted in the facilitation of several quintuple twin junctions that give rise to a five-fold twin structure along the film's growth direction. This type of grain growth promoted a pentagonal pyramid surface topology. Upon increasing the deposition rate or the addition of cobalt to reduce the stacking fault energy, an increase in the areal density of such features was observed. Correlated atomic contrast imaging by electron microscopy with atom probe tomography revealed the preference of phosphorus and residual oxygen Cottrell atmospheres around a dislocation network that would be required to accommodate the misorientation strain from a five-fold twin structure filling space. The ability to tune these structures, over a large area of material, offers grain boundary engineering opportunities to readily create novel surface topologies that can act, for example, as an array of field emitters or textured surfaces.