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.

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