X-ray photoelectron spectroscopy study of MgH2 thin films grown by reactive sputtering

In this work the indepth compositional variations of MgH2 thin films grown directly by reactive sputtering in H2 gas were studied over time. XPS was performed using a Thermo Scientific Theta Probe with monochromatic Al Kα radiation (hν = 1486.6 eV). Measurements at different sample depths were obtained by Ar+ ion sputtering, and high-resolution Mg 2p and O 1s spectra were used to quantify the data. Indications of differential charging effects were observed in the O 1s spectra. At the unsputtered surface a layer of Mg(OH)2 was found to grow with air exposure time. Underneath this layer, both MgH2 and MgO were present in near equal amounts, and deeper in the film there was an increasing amount of metallic Mg. Apart from the growth of Mg(OH)2 the film appeared to be stable in air over the time period of the experiment. Copyright © 2010 John Wiley & Sons, Ltd.