Reactive sputter-deposition and characterization of lead oxide films

Abstract

Lead and lead oxide containing films have been deposited on various substrates by radio frequency sputtering of a lead target in pure argon and argon–oxygen discharges. The sputter-deposited films were characterized by Rutherford backscattering spectroscopy, nuclear reaction analyses, and the x-ray diffraction technique. The composition, deposition rate, and crystalline structure of films were investigated as functions of the oxygen content (1.5%–50%) in the gas phase and sputtering power (50–200 W). The O/Pb atom number ratio increased rapidly up to one as the oxygen content in the discharge was varied from 1.5% to 6%. The films deposited under these conditions were composed of metallic lead, yellow orthorhombic β-PbO and PbO1.57 phases in variable proportions. Amorphous and noncataloged lead oxide phases were also formed for oxygen contents in the discharge higher than 6%. The effect of the composition of the deposited material on the residual stresses developed in the films was determined and related to the morphology of films examined by scanning electron microscopy. The friction properties of lead and lead oxide containing films deposited on stainless steel disks were determined by alumina ball-on-disk tribological tests conducted in air at a sliding speed of 3 cm s−1 under a load of 2 N. The friction coefficient was investigated as a function of the sliding distance, film thickness, and surface roughness of tribological disks and test temperature.