Deposition of magnesium hydride thin films using radio frequency reactive sputtering

Reactive sputter deposition of MgH_x thin films was performed using mixed hydrogen-argon plasma. This technique allows in-situ deposition of metal hydride films in contrast to the commonly applied ex-situ hydrogenation of metallic films. Partly transparent films were obtained and the formation of crystalline MgH₂ could be observed for thicknesses above about 200 nm. The formation of some metallic Mg in the films could not be avoided. Increased hydrogen loading by increased pressure, H₂:Ar ratio or reduced power produced films of porous structure that easily oxidise. More densely packed films remain stable for several months of air exposure. Post-deposition treatments in H-plasma showed evidence of hydrogenation of deposited films without the use of a catalysing capping film. Film properties are studied by X-ray diffraction, scanning electron microscopy and by optical and resistivity measurements.