Fabrication of a lateral field emission triode with a high current density and high transconductance using the local oxidation of the polysilicon layer

We have proposed and fabricated a lateral type polysilicon field emission triode using conventional photolithography and a LOCOS (local oxidation of polysilicon) in a lateral direction. The techniques employed in this study are very simple and allow for good reproducibility both in shaping sharp electrode tips and controlling the short cathode-to-gate interelectrode distance. The devices exhibit excellent electrical characteristics such as a low turn-on voltage of 14 V at V_GC = 0 V, a stable high emission anode current (I_A) of 92 μA/triode over 90 hours with a relatively small gate leakage current (I_G) of 0.23 μA/triode (I_A/I_G ≥ 400), and large transconductance (g_m) of 57 μS/5 triode at V_GC = 5 V and V_AC = 26 V. These superior field emission characteristics are believed to be due to an increased field enhancement effect which is related to the sharp cathode and gate tips shaped by the LOCOS as well as the high aspect ratio (tip height/radius of tip end) of the cathode tip.