Mr. Gautham Vijayan - Ph.D. Candidate
16/10/2025
David Wang Auditorium, 3rd Floor, Dalia Maydan Bldg.
13:30
Two-dimensional (2D) materials, particularly graphene and MoS2, have been extensively investigated due to their potential applications in electronics and tribology. Their intrinsic layered structure enables diverse stacking and rotational configurations, enabling the design of novel electronic devices with tunable properties. Moreover, structural superlubricity at the interlayer interfaces creates frictionless contacts, which facilitate the design and development of microscale and nanoscale electromechanical systems (MEMS/NEMS). Thus, comprehensive investigation of the electrical and mechanical characteristics of 2D materials are crucial in the design of atomically thin devices. The conductance anisotropy in multilayer MoS2 was investigated using spreading resistance measurements, and the effective resistivity (2.899Ωcm) was determined in agreement with a diffusive transport model. Both in-plane (~0.286Ωcm) and out-of-plane (~29.43Ωcm) resistivity were quantified, corresponding to an anisotropy ratio of ~100. For the comprehensive design of heterostructure devices based on 2D materials with rotational misalignment, the torsional energy across commensurate configurations in MoS2 (0.6384Nm/m2) and graphite (0.1533Nm/m2) were quantified. Furthermore, adhesion energies in these materials were evaluated to predict the slide to twisting mechanism at the interface. Finally, velocity and temperature dependent adhesion and friction in superlubric graphite interface is characterized. Friction increases with sliding velocity and decreases with temperature, following the thermally activated Prandtl–Tomlinson model associated with single asperity contacts, while adhesion increases with velocity and decreases with increase in temperature. The observed velocity-temperature dependence forces suggests that the mesoscopic sliding contact behaves as a rigid single-asperity system, similar to nanoscale Brownian systems, where thermal energy facilitates motion across potential barrier.