In Situ Field Emission of Density‐Controlled ZnO Nanowire Arrays

An effective in situ field-emission measurement system, in which the distance between the emitting source and counter electrode can be accurately measured and finely controlled by setting up a second stage inside a scanning electron microscopy chamber, is developed. It is found that nanowires with a density between 60 and 80 μm–2 (see figure) and of ca. 1 μm in length give the highest emitting current density.