Hall effect in Al–W thin films

The Hall coefficient, RH, electrical resistivity, ρ, and temperature coefficient of resistivity, α, of AlxW100−x (61≤x≤88) thin films and amorphous-like tungsten films are reported. The AlxW100−x films have been prepared by magnetron co-deposition of pure metals onto glass substrate. Films are X-ray amorphous for 63≤x≤86. Amorphous-like tungsten films (x=0) were obtained at sputtering conditions different from those applied for the preparation of Al–W alloys. The RH value is strongly dependent upon the alloy composition: it changes sign from positive to negative at x≈78, and exhibits a maximum for x≈68 at.%. With the decrease of Al content, ρ steeply increases and exhibits a maximum at x≈80 at.%. The temperature coefficient of the resistivity exhibits large negative values, with a well-defined minimum at x≈80. The Hall coefficient of films with 67≤x≤80 has also been determined at liquid nitrogen temperature, and the values obtained were the same as the room temperature values. Since the value of electrical resistivity of the examined alloys in the temperature interval from 77 to 300 K noticeably changes (10%), a significant anomalous contribution to the Hall effect is thus excluded.