Preparation and structure of AlW thin films

Abstract

Thin films of AlW alloys were prepared by co-deposition of pure aluminum and pure tungsten, each sputtered by an independently controlled magnetron source. The deposition rate at the substrate (glass, fused quartz, and alumina ceramic), positioned 5 cm away from the target surface was 0.1–0.2 nm/s for pure metals, and the final film thickness was a few μm. Completely amorphous films were obtained in the Al 80W 20–Al 67W 33 composition range. At higher tungsten content, the W(Al) solid solution and pure tungsten phases appeared. The amorphous alloys exhibit a high negative temperature coefficient of the electric resistivity, increasing with the aluminum content up to −5.5·10 −4 K −1. Finally, the amorphous AlW alloys exhibit a remarkable microhardness (6–7 GPa), and are structurally stable up to at least 400°C.