High-performance field-emission properties of boron nitride nanotube field emitters

Boron nitride nanotubes (BNNTs) have attracted considerable attention as a field emission material because of their high mechanical strength, high negative electron affinity, and high oxidation resistance. Nevertheless, the obtained field-emission properties of BNNTs have indicated poor emission performance, which is a very high turn-on electric field with a low emission current. We fabricated BNNT field emitters and investigated their field-emission properties. The field-emission properties of the BNNT field emitters were considerably enhanced compared to those of other BN nanomaterial-based field emitters. The turn-on and the threshold electric fields of the BNNT field emitter were 3.1 and 5.4 V/μm at the gap distance of 750 μm, respectively. Both the turn-on and the threshold electric fields of the BNNT field emitters were decreased by increasing the gap distance between the emitter tip and the anode electrode. Degradation of the emission current during field emission operation for 20 h showed no significant difference according to the gap distance. Emission current fluctuation of the BNNT field emitters showed that the smaller gap was more unstable than the larger gap. The enhanced emission properties are mainly attributed to the small diameter, high-quality, and straight structure of BNNTs as well as the stable network formation of the BNNT film with good mechanical and electrical contact between the BNNTs and the cathode electrode. The remarkable emission performance of the BNNT field emitters might have promising applications for various field-emission devices.