The effect of surface roughness on self-assembly tungsten nanoneedles induced by focused Ga+ ion beam bombardment

► We study the effect of surface roughness on the tungsten nanoneedles formation. ► Tungsten nanoneedles are self-assembled on tungsten surface with high roughness (Rz = 8.9 nm). ► A specific surface without nanoneedles formed on tungsten surface with low roughness (Rz = 1.4 nm) ► The nanoneedles are formed via self-organization processes, not by direct beam writing.