Electronic contribution to friction on GaAs: An atomic force microscope study

Abstract

The electronic contribution to friction at semiconductor surfaces was investigated by using a Pt-coated tip with 50 nm radius in an atomic force microscope sliding against an n-type GaAs͑100͒ substrate. The GaAs surface was covered by an approximately 1 nm thick oxide layer. Charge accumulation or depletion was induced by the application of forward or reverse bias voltages. We observed a substantial increase in friction force in accumulation ͑forward bias͒ with respect to depletion ͑reverse bias͒. We propose a model based on the force exerted by the trapped charges that quantitatively explains the experimental observations of excess friction.

Friction coefficient dependence on electrostatic tribocharging

“…Park et al78 studied the electronic contributions to friction in silicon pn junctions and Qi et al9 examined GaAs, while Altfeder and Krim10 studied levitation and atomic-scale friction of Fe on YBCO by magnetic force microscopy. They discussed the results considering the underlying atomic-scale electronic and phononic mechanisms that give rise to friction and the later concluded “that contact electrification and static electricity may play a significant role in the non-superconducting phase”.…”

“…Current work on friction acknowledges a number of surface composition (including adsorbed layers21), morphology, environment, geometry22 and other factors on friction coefficients. Great progress in this direction was obtained thanks to the introduction of scanning probe techniques that led to progress in relating surface molecular features to friction coefficients, in the nanoscale678910112324. To achieve control of the charging state of the surface, this work is often done on samples immersed in aqueous solutions25 that is adequate from the fundamental point of view but is not relevant to dry insulator surfaces.…”

Nondestructive tribochemistry-assisted nanofabrication on GaAs surface

“…However, the contact pressures P c during anodic oxidation by Pt-coated AFM tip was estimated to be 1 ~ 2 GPa when the tip radius was about 50 nm38, which was still higher than the contact pressure during the tribochemistry-assisted nanofabrication in this study. This means that the extent of lattice damage induced by tribochemistry-assisted method should not be worse than that by local anodic oxidation.…”

Current trends in the physics of nanoscale friction

“…With an atomic force microscope tip sliding on a silicon sample patterned with p and n regions, a variation in friction is observed as a function of the bias voltage [120]: a substantial increase in friction is found in the p-doped regions presenting a high carrier concentration near the surface. It appears however that the main contribution to the measured excess friction in contact is not due to the generation of electron-hole pairs but to the force exerted by trapped charges in the oxide surface [121].…”