Electric field control of the semiconductor-metal transition in two dimensional CuInP₂S₆/germanene van der Waals heterostructure

We propose a van der Waals heterostructure CuInP₂S₆/germanene by combining two dimensional ferroelectric semiconductor CuInP₂S₆ with germanene. By density functional theory calculations, we find that the metal-semiconductor transition can be realized in the CuInP₂S₆/germanene heterostructure by controlling the ferroelectric polarization direction. CuInP₂S₆ induces the sublattice imbalance of germanene by interface interaction and thus makes it become a normal semiconductor. Then, two opposite ferroelectric polarization states in CuInP₂S₆/germanene lead to a different band alignment and finally determine its metallic or semiconductor properties. Large transition barriers from ferroelectric to antiferroelectric phases ensure its stability at room temperature. This is a pure electric field controlled metal-semiconductor transition, which has great application potential for exploring nonvolatile ferroelectric switches and memory devices.