Figure 2
From: Observation of a giant two-dimensional band-piezoelectric effect on biaxial-strained graphene
Piezoelectric effect of graphene NEMS revealed by KPFM measurements. (a) Mechanical deformation of the suspended graphene membrane under different negative back-gate voltages. (b) Surface potential difference distribution of the bent membrane in a. The scan line follows the dashed line in Figure 1c. (c) Anomalous mechanical deformation of the suspended graphene membrane under different positive gate voltages. Up-bending is observed for large gate voltages. The scan line follows the dashed line in the inset. The edges between (monolayer) suspended graphene, graphite and the supported part are marked with dashed lines. Inset: Optical image of the device in panel c. (d) Temporal evolution of the mechanical deformation of the device under −5 V gate voltage scanned by an AFM tip biased at −1 V and (e) AFM tip biased at 1 V. AFM, atomic force microscope; KPFM, Kelvin probe force microscopy; NEMS, nanoelectromechanical systems.
