Experimental Decoding and Tuning Electronic Friction of Si Nanotip Sliding on Graphene

Abstract

Due to the coupled contributions of adhesion and carrier to friction typically found in previous research, decoupling the electron-based dissipation is a long-standing challenge in tribology. In this study, by designing and integrating a graphene/h-BN/graphene/h-BN stacking device into an atomic force microscopy, the carrier density dependent frictional behavior of a single-asperity sliding on graphene is unambiguously revealed by applying an external back-gate voltage, while maintaining the adhesion unaffected. Our experiments reveal that friction on the graphene increases monotonically with the increase of carrier density. By adjusting the back-gate voltage, the carrier density of the top graphene layer can be tuned from −3.9 × 10 12 to 3.5 × 10 12 cm −2 , resulting in a ∼28% increase in friction. The mechanism is uncovered from the consistent dependence of the charge density redistribution and sliding barrier on the carrier density. These findings offer new perspectives on the fundamental understanding and regulation of friction at van der Waals interfaces.

High-Temperature Superlubricity in MoS2/Graphene van der Waals Heterostructures

“…Tuning the carrier density of graphene from −2.1 × 10 12 cm –2 (hole) to 1.5 × 10 12 cm –2 (electron) electrostatically also could not introduce notable difference in the interface friction (Supplementary Figure S3). These results imply that the modulation in friction by applying current is not caused by an electronic contribution , or chemical group desorption, in line with the weak electron–phonon coupling in graphene, but mainly attributed to the lattice temperature modulation.…”