MgyNi1-y(Hx) thin films deposited by magnetron co-sputtering

TL;DR

This study synthesizes Mg-Ni metal and hydride thin films via magnetron co-sputtering, exploring their structural, optical, and electrical properties, with potential applications in smart windows and solar cells.

Contribution

It introduces a combinatorial co-sputtering method to deposit and analyze Mg-Ni hydride films, revealing phase diagrams and properties relevant for optoelectronic applications.

Findings

Reactive sputtering directly deposits high-purity Mg2NiH4 hydride.

Limited oxidation observed after months of ambient exposure.

Films show potential for optical control and photovoltaic applications.

Abstract

In this work we have synthesised thin films of MgyNi1-y(Hx) 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 MgyNi1-y films were deposited with pure Ar plasma while MgyNi1-yHx hydride films were deposited reactively with 30% H2 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 MgyNi1-y and MgyNi1-yHx, 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. MgyNi1-y and MgyNi1-yHx films might be applied for optical control in smart windows, optical sensors and as a semiconducting material for photovoltaic solar cells.