Electrostatic\nGating-Dependent Multiple Band Alignments\nin Ferroelectric α‑In<sub>2</sub>Se<sub>3</sub>/α-Te\nvan der Waals Heterostructures

The two-dimensional ferroelectric\nvan der Waals (vdW)\nheterojunction\nhas been recognized as one of the most promising combinations for\nemerging ferroelectric memory materials due to its noncovalent bonding\nand flexible stacking of various materials. In this work, the first-principles\ncalculations were performed to study the stable geometry and electronic\nstructure of α-In<sub>2</sub>Se<sub>3</sub>/α-Te, incorporating\nthe vdW correction via the DFT-D2 method. The reversal of the polarization\ndirection in α-In<sub>2</sub>Se<sub>3</sub> can induce a transition\nin the heterostructure from metallic to semiconductor, accompanied\nby a shift from type-III to type-I band alignment. These changes are\nattributed to variations in interfacial charge transfer. Analysis\nof the modulation effects of external electric fields reveals that\nthe P↑ α-In<sub>2</sub>Se<sub>3</sub>/α-Te configuration\nmaintains metallic, whereas the P↓ α-In<sub>2</sub>Se<sub>3</sub>/α-Te configuration exhibits a linear reduction in band\ngap. Furthermore, both heterostructural configurations will undergo\ntransitions to type-II band alignment transitions at 0.2 V Å<sup>–1</sup> and within a range from 0.2 to 0.3 V Å<sup>–1</sup> under external electric fields. Our findings offer valuable insights\nfor applications such as ferroelectric memory and static gate devices\nwith multiband alignment.