Mechanical and electrical properties of rf sputtered LaB 6 thin films on glass substrates

Abstract

LaB 6 films from 2000 to 5000 Å thick were prepared on glass substrates by rf magnetron sputtering. The effects of Ar discharge gas pressure from 5.3 to 5.3 × 10 −2 Pa on the structural, electrical and mechanical properties of the films were examined. The structural characteristics were analyzed by X-ray diffraction and emission spectrochemical technique (ICP). The electrical film resistivity was measured using a four-point probe technique. The internal stress and adhesion of films were determined by the bending-plate method and the microtribometer, respectively. The deposition process of rf magnetron sputtering was studied by a quadrupole mass filter system. The results indicated that an increase in Ar gas pressure in sputtering depositions increased the atomic ratio B/La in LaB films. The most preferable Ar gas pressure for stoichiometric LaB 6 formation was found to 10 −1 Pa and it was also suitable for producing high quality films as electrodes. The main crystalline orientation of the sputtered LaB 6 films was (100) which is the orientation of lower work function (2.4–2.5 eV) in LaB 6 crystals.