Nanometer-scale surface features of the carbon film drastically improving field emission characteristics

In this study, the FE current is measured pixel-by-pixel by setting the bias voltage at a value much larger than the tip work function after temporarily opening the feedback loop for the constant current (CC) operation of STM, where the electrons tunnel through a triangle potential barrier, as shown in Figs. 1 (a) and (b). Figs. 2 (a) and (b) show the STM and FE images simultaneously obtained from the HOPG surface with defects. From these images, we recognize that the FE currents are higher just at the defect sites, which is consistent with theoretical expectations [6]. And we confirm a nanometer-scale spatial resolution of this imaging method. The local tunneling barrier height (LBH) imaging, which is very sensitive to the electronic properties, is also used.