A capacitor is provided which comprises: a first structure comprising metal; a second structure comprising metal; and a third structure between the first and second structures, wherein the third structure comprises an improper ferroelectric material. In some embodiments, a field effect transistor (FET) is provided which comprises: a substrate; a source and drain adjacent to the substrate; and a gate stack between the source and drain, wherein the gate stack includes: a dielectric; a first structure comprising improper ferroelectric material, wherein the first structure is adjacent to the dielectric; and a second structure comprising metal, wherein the second structure is adjacent to the first structure.