Polarization-Induced Band-Alignment Transition and Nonvolatile p-n Junctions in 2D Van der Waals Heterostructures

2D van der Waals (vdW) p-n junctions based on vertically stacked atomically thin semiconductor materials have shown tremendous potential in high-performance integrated electronics and optoelectronics. However, unlike traditional semiconductors, the conventional doping methods to achieve p-type and n-type doping in 2D semiconductors remain a large challenge due to their ultrathin structures with limited physical space. Here, by means of density functional theory computations, a nonvolatile doping strategy to obtain self-defined p-n junctions in 2D vdW heterostructures created by assembling monolayer transition metal dichalcogenides (TMDs) on polar semiconductors (PSs) is reported. The calculated results show that the quantum-confined Stark effect causes the band inclination of 2D PSs along the polarization direction, which allows to manipulate the type of band alignment and spatial distribution of carriers in the heterostructures via the polarization modulation. In particular, the realization of nonvolatile p-n junctions in type-III TMD/PS heterostructures with ultrahigh carrier concentration (approximate to 10(13) - 10(14) cm(-2)) is demonstrated, and the spatial distribution of charge carriers in the heterostructures can be tuned by the polarization switching. This work provides a nondestructive doping strategy to obtain programmable vdW p-n junctions with high carrier concentration and band-engineering approach for the development of versatile 2D electronics and optoelectronics.

Automated summary

A nonvolatile doping strategy is reported for obtaining self-defined p-n junctions in 2D vdW heterostructures created by assembling monolayer transition metal dichalcogenides on polar semiconductors. The results show that the quantum-confined Stark effect plays an important role in spatial distribution, allowing manipulation of carrier types through polarization modulation. This work demonstrates the realization of nonvolatile p-n junctions with high carrier concentration in TMD/PS heterostructures and provides a band-engineering approach for versatile 2D electronics and optoelectronics development.