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 mu m(-2) (see figure) and of ca. 1 mu m in length give the highest emitting current density.