Native Oxide Seeded Spontaneous Integration of Dielectrics on Exfoliated Black Phosphorus

Two-dimensional (2D) semiconductors have been a central focus for next-generation electronics and optoelectronics owing to their great potential to extend the scaling limits in a silicon transistor. However, due to the lack of surface dangling bonds in most 2D semiconductors, such as graphene and transition metal dichalcogenides (TMDs), the direct growth of the high-κ film on these 2D materials via an atomic layer deposition (ALD) technique often produces dielectrics with poor quality, which hinders their integration in the modern semiconductor industry. Here, we comprehensively investigate the ALD growth of the Al₂O₃ layer on 2D exfoliated black phosphorus (BP). Intriguingly, we found that the 2D BP with "silicon-like" characteristics possesses a native surface oxide layer PO after air exposure. The PO-induced surface dangling bonds enable the spontaneous integration of the high-quality Al₂O₃ layer on the BP flake without any pretreatments to functionalize the surface. Additionally, the Al₂O₃ layer could effectively passivate BP to prevent its degradation in ambient conditions, which addresses the most serious problem of the BP material. Moreover, the Al₂O₃-encapsulated BP field-effect transistor (FET) exhibits good electrical transport performance, with a high hole mobility of ∼420 cm² V^-1 s^-1 and electron mobility of ∼80 cm² V^-1 s^-1. Moreover, the high-quality Al₂O₃ layer can also be integrated into the top-gated BP transistor and inverter. Our findings reveal the silicon-like characteristics of BP for the high-κ ALD dielectric growth technology, which promises the seamless integration of 2D BP in the modern semiconductor industry.