Dielectric properties of thin ferroelectric Sn$_2$P$_2$S$_6$ films deposited by thermal evaporation

The structure, microstructure, and temperature and field dependences of the dielectric properties of thin (0.5–8.0$\mu$m) Sn$_2$P$_2$S$_6$ ferroelectric films deposited onto glass and aluminum foil substrates by thermal vacuum evaporation in a quasi-closed volume are studied. The film-thickness and frequency dependences of the dielectric properties and the unipolarity of the C–V characteristics are explained by the presence of near-surface Schottky-type barrier layers.