Stable field emission from planar-gate electron source with MWNTs by electrophoretic deposition

A planar-gate electron source with multi-wall carbon nanotubes (MWNTs) has been successfully fabricated by conventional magnetron sputtering, lithography and electrophoretic deposition (EPD). The optical microscopy showed that he MWNTs purified in H2SO4/HNO3 solution were selectively deposited on cathode. High resolution transmission electron microscopy (HRTEM) images and Raman spectra demonstrated that some MWNTs was destroyed and generated some defect. Field emission results indicated that the emission current of this triode structure is completely controlled by gate voltage. The turn-on voltage of electrophoretic deposited MWNTs cathode at current density of 1 μA/cm2 was lower than that of screen printed MWNTs cathode besides better emission uniformity. In addition, the emission current fluctuation was less than 3% for 400 min. All the results indicate that the fabricated electron emission source has a good field emission performance and long lifetime.

► CNTs were selectively deposited on the cathode rather than gate electrode by EPD.
► Field emission (FE) characteristics were completely controlled by gate voltage.
► FE performance by EPD is much better than that of screen printed CNTs cathode.
► The fabricated electron source has a good field emission property and long lifetime.