Figure 4: Measurement results on a ZnO nanowire.

(a,c) are series of SEM images of the measurement on the Au particle and the sidewall region below it at a ZnO nanowire respectively with different external voltage V. (b,d) are their corresponding results of d – x versus the external voltage. The red curves are the results fitting by a parabola function, which show that their CPDs are 0.58 V and 0.17 V respectively when comparing to the Au-coated probe. The insets are the corresponding schematic diagrams of the measurements.