1. A memory device, comprising: a substrate layer including a first electrode; and a two-terminal memory layer comprising: a first layer coupled to the first electrode, wherein the first layer comprises a first semiconductor material in an amorphous phase; a second layer coupled to the first layer, wherein the second layer comprises a second semiconductor material in a polycrystalline phase; a resistive switching material (RSLM) layer coupled to the second layer; an active metal layer coupled to the resistive switching material layer; and a second electrode coupled to the active metal layer.