Self-doped p–n junctions with high carrier concentration in 2D GaN/MoSSe heterostructures: a first-principles study

Abstract

Designing p–n junctions without introducing foreign atoms has attracted considerable attention, especially as far as high carrier concentrations are concerned. Here, we systematically investigate the structural and electronic properties of polar GaN/MoSSe by first-principles calculations. The diversity of GaN and MoSSe structures and their polarization leads to versatile heterostructures with different electronic behaviors. Particularly, the band alignment can be effectively modified from type-I or type-II to type-III, forming a self-doped p–n junction. Interestingly, the carrier concentration in self-doped p–n junctions is large (>3.48 × 10¹² cm⁻²). This unique behavior is mainly attributed to the charge redistribution and intrinsic electric field induced by polarization, leading to a shift of the band edge positions and induction of the quantum Stark effect. This work provides a perspective for regulating vdW heterostructures and shows possibilities for designing self-doped p–n semiconductors for low-power and multi-functional device applications.