The drastic temperature rise of multiwall carbon nanotubes (MWCNTs) in response to microwave irradiation was applied to weld a MWCNT paste on a polymer substrate within a few seconds. It provides a strong bonding between the MWCNT and polymer without thermal damage to the substrate. A flexible field emitter was made from MWCNT microwave welded on polycarbonate, showing excellent electrical conduction and field-emission properties even under bending. The field emitter works with a turn-on voltage of 0.8V∕μm due to the direct electron transfer. By this method, printed circuits and field-emission devices can be processed simultaneously within seconds leading to important applications in flexible electronic devices.

Unidirectional single crystalline InN nanoemitters were fabricated on the silicon ͑111͒ substrate via ion etching. These InN nanoemitters showed excellent field emission properties with the threshold field as low as 0.9 V / m based on the criterion of 1 A / cm 2 field emission current density. This superior property is ascribed to the double enhancement of ͑1͒ the geometrical factor of the InN nanostructures and ͑2͒ the inherently high carrier concentration of the degenerate InN semiconductor with surface electron accumulation layer induced downward band bending effect that significantly reduced the effective electron tunneling barrier even under very low external field.