Characterization of a superlubricity nanometer interface by Raman spectroscopy

Despite being known for almost two decades, the use of micro-/nano-electromechanical systems in commercial applications remains a challenge because of stiction, friction, and the wear of the interface. Superlubricity may be the solution to these challenges. In this paper, we study factors affecting the realization of superlubricity. Raman spectroscopy and other methods were used to characterize a graphite interface which can realize superlubricity and another graphite interface which cannot realize superlubricity. Raman spectra of the interfaces were obtained with the mapping mode and then processed to obtain the Raman images of the characteristic peaks. The Raman spectra provided the distribution of the surface defects and probed defects. Combined with atomic force microscopy and x-ray photoelectron spectroscopy, the Raman spectra show that the sp(3) carbons and carbon-oxygen bond stuck at the edge of the graphite mesa are some of the determinants of large-area superlubricity realization. The characterization results can also be used to understand the friction and wear of large-area superlubricity, which are important for development and application of superlubricity. Furthermore, the methods used in this study are useful techniques and tools for the mechanism analysis of other nanometer interfaces.