Mg _yNi _1-y(H _x) thin films deposited by magnetron co-sputtering

In this work we have synthesized thin films of Mg _yNi _1-y(H _x) metal and metal hydride with y between 0 and 1. The films are deposited by magnetron co-sputtering of metallic targets of Mg and Ni. Metallic Mg _yNi _1-y films were deposited with pure Ar plasma while Mg _yNi _1-yH _x hydride films were deposited reactively with 30% H ₂ in the Ar plasma. The depositions were done with a fixed substrate carrier, producing films with a spatial gradient in the Mg and Ni composition. The combinatorial method of co-sputtering gives an insight into the phase diagram of Mg _yNi _1-y and Mg _yNi _1-yH _x, and allows us to investigate structural, optical and electrical properties of the resulting alloys. Our results show that reactive sputtering gives direct deposition of metal hydride films, with high purity in the case of Mg _∼2NiH _∼4. We have observed limited oxidation after several months of exposure to ambient conditions. Mg _yNi _1-y and Mg _yNi _1-yH _x films might be applied for optical control in smart windows, optical sensors and as a semiconducting material for photovoltaic solar cells.