Study of aluminum oxide films by ion-induced x rays and Rutherford backscattering

Abstract

Oxide films of about 0.5 and 48 μg (Al2O3)/cm2 on aluminum substrates were studied using 400‐keV protons and He+ions as probes. Energy analysis of the ion‐induced x rays and the backscattered particles provided compositional information about the films. A Si(Li) detector was used to detect the O K α and AlK α,βx rays and a surface barrierdetector was used to detect the backscattered particles. Since the samples and detectors were in the same high‐vacuum chamber during all measurements, this approach afforded a direct in situ comparison of the two techniques. Owing to the energy resolution limitation of the surface barrierdetector, only the ion‐induced x‐ray measurements provided quantitative thickness measurements of the thin oxide. For the thicker oxide both methods provided thickness information, and the stoichiometry of the oxide was obtained from the backscattering data. In addition proton stopping powers were obtained from the backscattering measurements.