Field effect transistors having a ferroelectric or antiferroelectric gate dielectric structure are described. In an example, an integrated circuit structure includes a semiconductor channel structure includes a monocrystalline material. A gate dielectric is over the semiconductor channel structure. The gate dielectric includes a ferroelectric or antiferroelectric polycrystalline material layer. A gate electrode has a conductive layer on the ferroelectric or antiferroelectric polycrystalline material layer, the conductive layer including a metal. A first source or drain structure is at a first side of the gate electrode. A second source or drain structure is at a second side of the gate electrode opposite the first side.