Sputter-deposited amorphous-like tungsten

Thin tungsten films were prepared by sputtering of pure tungsten in a cylindrical magnetron device. The XRD-patterns of tungsten films deposited at 3.5 Pa argon pressure regularly exhibited only a very broad signal centered at 2θ≈40°—a distinctive mark of amorphous metals and alloys. The grain size of such amorphous-like tungsten material was estimated to be approximately 2 nm, while SAXS measurements yield a radius of gyration of 1.4 nm. Its thermal coefficient of the electric resistivity at room temperature was negative—a characteristic feature of amorphous metals and alloys. Thermal stability of the amorphous-like tungsten films was investigated by isochronal heating up to 720 °C in vacuum, with continuous monitoring of electric resistivity. The obtained results indicate that amorphous-like tungsten is thermally stable up to 450 °C.