Interfacial Charge Transfer Driven Enhanced Transport and Thermal Stability in Graphene-MoS2 Vertical Heterostructure Field-Effect Transistors

Abstract

In this work, we demonstrate interfacial charge transfer-driven transport enhancement in few-layer graphene monolayer MoS2 vertical heterostructure field-effect transistor. Raman scattering and Raman intensity mapping results confirm the successful stacking of FL graphene on ML MoS2. Pronounced photoluminescence (PL) quenching of MoS2 and spectral redshift in the heterostructure suggest efficient interlayer charge transfer and strong electronic coupling at the vdW interface. Electrical measurements show enhanced drain current, field-effect mobility, and conductivity in Gr-MoS2 device compared to pristine MoS2 transistor with Ag contacts. The energy band considerations under equilibrium and gate bias conditions suggest improved Fermi-level alignment and reduced effective Schottky barrier effects at the graphene-MoS2 interface, enabling efficient carrier injection. Temperature-dependent transport (300-400 K) reveals phonon-dominated mobility and conductivity degradation in both devices; however, the heterostructure exhibits significantly suppressed performance degradation. The mobility enhancement factor increases from ~1.6 at 300 K to ~4.0 at 400 K, accompanied by a corresponding improvement in conductivity stability, demonstrating superior thermal robustness for the Gr-MoS2 heterostructure. The power-law analysis indicates that transport in pristine MoS2 is influenced by both intrinsic phonon scattering and additional thermally activated extrinsic processes such as contact and interfacial effects, whereas the weaker temperature dependence in the Gr-MoS2 device reflects moderated extrinsic contributions and transport behaviour approaching a predominantly phonon-limited regime. These findings demonstrate graphene contact engineering as a viable pathway toward improved performance and thermally stable two-dimensional semiconductor electronics.