Structural and optical properties of thin lead oxide films produced by reactive direct current magnetron sputtering

Abstract

The structural and optical properties of thin lead oxide films were studied. Thin films were prepared by reactive dc magnetron sputtering of lead (Pb) targets in an Ar/O2 mixture. The structure has been determined by x-ray diffraction measurements, which show that crystalline lead oxide films of different composition (PbO, PbO1.44, Pb2O3, and PbO2) have been formed upon increasing oxygen flow (partial pressure). This result is confirmed by Raman spectroscopy. The effect of postdeposition annealing on the structural properties of PbO films reveals that the film structure is governed by both energetics and kinetics. X-ray reflectivity measurements were used to determine the thickness, density, and roughness of the films. The calculated film density values are almost equal to the bulk density of the material, showing that compact, nearly void free films are formed. The optical properties of the films have been studied from the reflectance and transmittance spectra recorded by optical spectroscopy measurements from 10 000 (1.24 eV) to 50 000 (6.21 eV) cm−1. From these data we have determined optical properties such as the dielectric function, the optical band gap Eg and the refractive index n as well as the film thickness.