Few-layered MoS₂ Based Vertical van der Waals p-n Homojunction by Highly-efficient N₂ Plasma Implantation

2D transition metal dichalcogenides have shown great potential for next-generation microelectronic devices owing to their ability to prolong the life of Moore's law by mitigating the short-channel effect. Recently, many efforts have been made on doping 2D films to create p-n junctions, in which plasma implantation has been placed great expectations due to its CMOS process compatibility. However, ultrathin vertical 2D p-n homostructure with excellent rectification behaviors have rarely been studied so far. Herein, MoS₂ van der Waals p-n homojunctions are fabricated by highly efficient N₂ plasma implantation. Kelvin probe force microscope reveals the surface potential difference of ≈130 mV between n-MoS₂ and p-MoS₂. The fabricated field-effect transistor (FET) presents a high rectification ratio up to 3.1 × 10^–3 at the gate bias V_GS = 20 V, which is over 20 times larger than that of the vertical homojunction obtained by surface chemical doping. The forward current is mainly dominated by both the interlayer recombination and band-to-band tunneling, while the ultra-low reverse current in the order of 10 pA is governed by direct tunneling. The results demonstrate a new CMOS-compatible way to fabricate vertical 2D homojunction, which is the basic structure of many low-dimensional microelectronic devices.