Film thickness change of switchable mirrors using Mg3Y alloy thin films due to hydrogenation and dehydrogenation

Switchable mirrors based on magnesium-yttrium alloy thin films were prepared by a direct-current magnetron sputtering method. The changes in the film thickness of the mirrors due to hydrogenation and dehydrogenation have been investigated using atomic force microscopy and X-ray reflectometry. As a result of first hydrogenation of a switchable mirror, the thickness was expanded by ~15%, while as a result of dehydrogenation, the thickness was compressed by only ~2%. From the switching processes, the thickness changed by ~2% on the following optical switching. This small change may cause high switching durability of Mg-Y switchable mirrors.