α-In2Se3/Nb-doped MoS2 heterojunction: a first-principles study

Abstract The α-In2Se3 material is a 2D ferroelectric semiconductor whose structural asymmetry gives it spontaneous polarization properties, and exhibits a direct bandgap band structure when it is multilayered. α-In2Se3 is an n-type semiconductor, which is usually used in experiments to form heterojunctions with p-type semiconductors to prepare photodetectors. In this paper, we designed α-In2Se3/Nb-doped MoS2 heterojunction, because Nb doping is a good p-type dopant for MoS2. Our research shows that: the heterojunction exhibits type-Ⅱ band alignment; the band offset can be changed by the out-of-plane polarization direction; doping can modulate the Fermi energy level position of MoS2 and thus further modulate the band alignment and band offset. The α-In2Se3/Nb-doped MoS2 heterojunction is expected to be applied to the field of photodetectors, and we proposed a method to adjust the band alignment of the heterojunction by adjusting the doping concentrations.