Negative capacitance field-effect transistor (NCFET) and ferroelectric field-effect transistor (FE-FET) devices and methods of forming are provided. The gate dielectric stack includes a ferroelectric gate dielectric layer. An amorphous high-k dielectric layer and a dopant-source layer are deposited sequentially followed by a post-deposition anneal (PDA). The PDA converts the amorphous high-k layer to a polycrystalline high-k film with crystalline grains stabilized by the dopants in a crystal phase in which the high-k dielectric is a ferroelectric high-k dielectric. After the PDA, the remnant dopant-source layer may be removed. A gate electrode is formed over remnant dopant-source layer (if present) and the polycrystalline high-k film.