Polarization Induced Self-Doping Effects and P-N Junctions in Heterostructures  Based on F-Gan-H Stacking

Self-doping p-n junctions at atomically thin materials is the perfect solution for the challenges impeding 2D materials in devices. Here, using density functional theory (DFT) based on first-principles calculations, we find that in seven surfaces passivated buckled 2D GaN monolayers, the F-GaN-H is not only with the strongest polarity but also with the most stable structure. Based on the polarization direction and intensity of the F-GaN-H, heterostructures are constructed based on the F-GaN-H and graphene (G) with different stacking styles. The electronic properties suggest that the self-doping effects are induced, and the n-, p-doping type and level of self-doping can be effectively modulated by the direction and intensity of polarization of the F-GaN-H stacking. Furthermore, the atomically thin p-n junction is naturally formed in the G/F-GaN-H/G sandwich heterostructures, and the graphene layers become metallic acting as electrodes and achieving natural low-resistance contact. The results in our work would be a theoretical foundation for simplify the device fabrication process of two-dimensional electronic devices based on 2D GaN layer.