Local field emission of electrons from an individual boron nanowire at nanometer electrode separation

The field emission of individual β-rhombohedral boron nanowire was studied by ultrahigh vacuum four-probe scanning tunneling microscopy (STM) system for the first time. ► A reproducible and stable emission current is obtained, which is comparable to carbon nanotubes. ► The field emission properties were also studies at nanoscale electrode distance. ► An obvious deviation was observed when the electrodes getting too close. This deviation is tentatively assumed to due to the invalidation of free electron cloud approximation in FN theory. The field electron emission properties of an individual β-rhombohedral boron nanowire (β-r BNW) with electrode separation at nanoscale have been studied by ultrahigh vacuum four-probe scanning tunneling microscope (STM) system. A reproducible and stable emission current can be obtained. The maximal emission current density of individual boron nanowire is about 5×104A/cm2 at a low bias voltage (80V). An obvious deviation from the Fowler–Nordheim (FN) theory appears, when the electrode separation reduced below 120nm. This deviation is tentatively assumed to due to the invalidation of free electron cloud approximation in FN theory.