Planar Field Emission Current from Individual Carbon Nanotubes

Carbon nanotube (CNT) planar field emitters were fabricated on a SiO2/Si substrate. The anode, cathode and CNT all lay on the same substrate for the promising advantage of intergratibility with planar technology. The emission current was acquired in a scanning electron microscope (SEM). Despite the asymmetry (tip-electrode) of our field emission sample, a symmetrical I V curve consistent with the Fowler-Nordheim theory was acquired. Using Zener theory on quantum tunneling in insulators, the observed phenomenon was explained to be a possible leakage current through the insulating SiO2 instead of real field emission. Moreover, the simulated local electric fields at the emitter apex exclude the possibility of an accountable emission current. Our results are of great importance in studying planar field emission since it draws attention to avoid mistaking leakage current for the actual field emission current in planar field emission devices.