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The deformation and stacking of graphene significantly affect the overall electronic and mechanical properties. The graphene sheets are easily stacked each other due to van der Waals attraction. The folded characteristic may prevent graphene stacking and increase the d-spacing between graphenes. It can easily form dense graphene structures with high surface area and be applied on electrode materials of battery, nano-composites and so on. The traditional topographic mapping of atomic force microscope (AFM) is hard to measure the characters of surface deformation and distinguish the folding and stacking. In this study, we apply a novel quantitative nano-mechanical AFM to analyze the reduced-graphene oxide (r-GO). The results indicate that the novel AFM system could recognize the difference between folding and stacking of r-GO effectively. Nevertheless, the images including topography, deformation, adhesion, and elastic modulus show the different phenomena between measuring region, which appears that status on measuring region are folding and stacking, respectively.

We have employed photo-assisted conductive atomic force microscopy (PA-CAFM) to obtain high-resolution current images on III-nitride surfaces. From the statistical results of current distribution, it is revealed that the full-width at half-maximum (FWHM) value is very sensitive to the dislocation density of III-nitride films even if the dislocation density is very low (~10^8cm^-^2), suggesting that the FWHM value of current statistics can be an indicator of III-nitride quality. The results acquired by PA-CAFM are consistent with those obtained from etching-pit density and X-ray diffraction measurements. In addition, it is also revealed that PA-CAFM can observe the current distribution of InN dots without external bias influences, directly indicating the dependence of InN dots and dislocations. Our experimental results indicate that PA-CAFM is a promising method for investigating the electrical and structural properties of a nanometric area in III-nitride materials.