Thermally evaporated (oxide) iron on an alumina barrier layer by ToF-SIMS

The authors report the positive and negative ion time-of-flight secondary ion mass spectrometry spectra using Bi32+ primary ions at 50 keV of an Fe film (6 nm) that had been thermally evaporated on a thin film of alumina (ca. 35 nm) on a silicon wafer. This surface had been exposed to the air; it had previously been shown by x-ray photoemission spectroscopy (XPS) to be entirely oxidized. The positive ion secondary ion mass spectrometry spectrum shows Fe+, FeH+, and FexOyHz+ species. The negative ion spectrum shows FeOH−, FexOyHz−, and OH− species.