Structure and stability of sputter deposited beta‐tungsten thin films

The structure and stability of thin tungsten films prepared by radio frequency magnetron sputter deposition have been studied by x‐ray diffraction and x‐ray photoelectron spectroscopy. The structure of these films has been found to systematically evolve from the metastable A15 β‐W phase to the equilibrium A2 α‐W phase with decreasing oxygen impurity concentration. Within the β‐W phase a decrease in the concentration of incorporated oxygen results in a monotonic decrease in the lattice parameter of the unit cell until the β‐W phase eventually becomes unstable, and the α‐W phase is formed.