Amorphous insulating MoS${}_x$ films deposited by magnetron sputtering as a low-index optical coating

Abstract

While much effort are now concentrated on exploration of crystalline form of MoS${}_2$ as a two-dimensional material, we show that room-temperature DC magnetron sputtering from pressurized MoS${}_2$ powder target produces amorphous MoS${}_x$ films with optical properties fundamentally different from those of crystalline MoS${}_2$. The films were found to have a sulfur content of approximately $x=1.8$, indicating sulfur deficiency. They are optically isotropic and exhibit rather low optical losses, with a refractive index of about 2 over the visible and near-infrared spectral range. Their compatibility with lift-off lithography and dry etching makes amorphous MoS${}_x$ a promising material for integrated photonic applications.

6 pages, 5 figures