High-Mobility Junction Field-Effect Transistor via Graphene/MoS₂ Heterointerface

Monolayer molybdenum disulfide (MoS₂) possesses a desirable direct bandgap with moderate carrier mobility, whereas graphene (Gr) exhibits a zero bandgap and excellent carrier mobility. Numerous approaches have been suggested for concomitantly realizing high on/off current ratio and high carrier mobility in field-effect transistors, but little is known to date about the effect of two-dimensional layered materials. Herein, we propose a Gr/MoS₂ heterojunction platform, i.e., junction field-effect transistor (JFET), that enhances the carrier mobility by a foctor of ~10 (~100 cm²V^-1s^-1) compared to that of monolayer MoS₂, while retaining a high on/off current ratio of ~10⁸ at room temperature. The Fermi level of Gr can be tuned by the wide back-gate bias (<i>V</i>_BG) to modulate the effective Schottky barrier height (SBH) at the Gr/MoS₂ heterointerface from 528 meV (<i>n</i>-MoS₂/<i>p</i>-Gr) to 116 meV (<i>n</i>-MoS₂/<i>n</i>-Gr), consequently enhancing the carrier mobility. The double humps in the transconductance derivative profile clearly reveal the carrier transport mechanism of Gr/MoS₂, where the barrier height is controlled by electrostatic doping.