β -phase tungsten nanorod formation by oblique-angle sputter deposition

Abstract

We report the creation of an unusual simple cubic β-phase W(100) nanorods with a pyramidal tip having four (110) facets using an oblique-angle sputter deposition technique with substrate rotation (also known as glancing-angle deposition). During the oblique-angle deposition, both β-phase W(100) and α-phase W(110) islands exist at the initial stages of growth. The β-phase W(100) islands grow taller due to the lower adatom mobility on these islands. The taller islands survive in the competition and form isolated nanorods in the later stages of growth. This is in contrast to the sputter deposition at normal incidence, where only the thermodynamically stable bcc α-phase W(110) polycrystalline films were formed when the film grows to a certain thickness.