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

Abstract

Abstract2D 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 VGS = 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.

Highly Tunable Lateral Homojunction Formed in Two-Dimensional Layered CuInP2S6 via In-Plane Ionic Migration

“…The flourish of various van der Waals (vdW) materials and the need for device miniaturization have stimulated the rapid growth of interest in the fabrication of vdW-based p - n junctions, which have great potential in modern functional diversity electronic and optoelectronic devices. , In this direction, significant efforts have been devoted to develop the p - n heterojunctions. , However, lattice mismatch-induced impurities , and discontinuous band alignments , are inevitably introduced at the interface, which deteriorate the quality and performance of device. Compared with heterojunctions, the homojunction, which is achieved through the modulation of charge type and density in different regions of the same material, can effectively solve these problems. − To date, conventional routes to construct lateral p - n homojunctions in 2D vdW material include laser irradiation, , plasma doping, and layer-engineering. , However, these approaches usually involve a complicated device fabrication process and tend to suffer from chemical contamination. Therefore, a controllable contamination free method is highly desired.…”

“…Compared with heterojunctions, the homojunction, which is achieved through the modulation of charge type and density in different regions of the same material, can effectively solve these problems. 9−14 To date, conventional routes to construct lateral p-n homojunctions in 2D vdW material include laser irradiation, 15,16 plasma doping, 14 and layer-engineering. 17,18 However, these approaches usually involve a complicated device fabrication process and tend to suffer from chemical contamination.…”

Anisotropic charge transfer and gate tuning for p-SnS/n-MoS2 vertical van der Waals diodes

“…6a, for thinner diodes, such as 3.2 nm and 6.6 nm diodes, V p is limited by the low density of states and thin thickness of SnS. Thus, V p is lower than Φ B , and the tunneling can be explained by the DT model, in which electrons (holes) directly tunneling through SnS (MoS 2 ) dominate the minority transport at V D < 0 V. Very similar to the thin n-doped p-MoS 2 PN homojunction, 1 V p is usually lower than Φ B even under a positive V G as high as +50 V, which greatly restricts the DT transport and leads to a relatively small reverse current, as shown in Fig. 2c–f and Fig.…”

“…As a result, direct and/or Fowler–Nordheim tunneling (DT and/or FNT) is likely to occur at reverse V D and the mechanism is sensitive to the barrier thickness. 1 The balance between the band bending ( V p ) of the conduction band of p-SnS and barrier height ( Φ B ) at the SnS/drain interface determines the tunneling type. As shown in Fig.…”

“…The rise of 2D semiconductor materials has paved a new way to alleviate the short channel effect problem, which blocks the further reduction of the size of Si-based transistors. 1 For 2D semiconductor devices, electrons move within atomically thin layer channels, 2,3 which greatly reduces the characteristic length, facilitating transistors to miniaturize to the next technology node of sub-3 nm. [4][5][6][7] In particular, when a p-n junction is formed by vertically stacking two kinds of van der Waals semiconductors, e.g., MX 2 (M = Mo, W, Pt, Re; X = S, Se, Te)-based transition metal dichalcogenides (TMDs), [8][9][10][11][12][13][14][15][16] low leakage current and good rectification performance can be established due to the sharp interfaces.…”