High-performance reconfiguring bilayer MoS2 transistors based on multi-pathway charge-injection co-regulation mechanism

• A reconfiguring nucleation strategy of gradient-varying gas flow to achieve bilayer-MoS 2 is propose by modified multi-source CVD method. • The high-performance bi-MoS 2 FETs with high on-current of 55 μA/μm, high electron mobility 39.7 cm 2 /Vs and current on/off ratio 3.5 × 10 8 is constructed, and multi-pathway charge-injection mechanisms with van der Waals bonding and strong bonding (for top-edge contact) is proposed. • The discontinuous in the conduction and valence bands of 2L/1L junction is demonstrated by finite element simulation, which corresponds to the rectifying characteristics of 2L-1L transistor. As silicon-based transistor technology approaches the limits of Moore’s Law, atomically-thin layered transition metal dichalcogenides (TMDCs) has great potential for advanced electronics applications, especially bilayer molybdenum disulfide (bi-MoS 2 ). However, the energy band properties and charge-transport mechanism among MoS2 and electrodes are still not well investigated for 2D transistors, especially interface junctions of monolayer and bilayer MoS 2 . Here, we successfully synthesized bilayer MoS 2 by modified chemical vapor deposition (CVD) by adjusting separated multi-gas-flow. The bilayer-MoS 2 field-effect transistors (FETs) show superior performance with high current density of 55 μA/μm and Schottky barrier height of 26 meV compared with monolayer MoS 2 FETs. We propose multi-pathway charge-transport co-regulation mechanism dominated by Schottky and tunneling currents to describe the electrical response for bi-MoS 2 edge-top contact FETs. The devices with the structure of pure bi-MoS 2 (2L-2L) and junctions (2L-1L) are constructed and demonstrate high electron mobility (39.7 cm 2 /Vs and 24.2 cm 2 /Vs) and current on/off ratio (3.5 × 10 8 and 1.6 × 10 8 , respectively). Finite element simulation and experiments reveal discontinuous gradient variations of thickness-dependent 2L/1L junction, which are associated with the rectifying properties of the 2L/1L FETs. This work not only provides a feasible approach for bilayer TMDCs crystals, but also broadens rational design of future electronic and optoelectronic devices.