Ellipsometric study of optical switching processes of Mg-Ni based switchable mirrors

Optical switching processes of Mg-Ni based switchable mirrors were studied “in situ” using spectroscopic ellipsometry. Ellipsometric angles Ψ and Δ of the switchable mirrors varied drastically as a result of hydrogenation and dehydrogenation. These variations are due to transformation between metal and semiconductor of Mg-Ni layers. We have clarified the switching processes by analyzing these variations using the following two steps. First, we evaluated dielectric functions of five materials: metal, hydrogen-solid-solution, hydride states of Mg-Ni alloy, and metal and hydride states of Pd. Using these dielectric functions, we then varied thickness and concentration of each layer.