CONE-GATED AND WEDGE-GATED FIELD EMITTER DIODE AND MICROTRIODE MODELING

Two kinds of vertical-type gated field emission diodes (GFED) and fiel d emission microtriodes (FEMT) are modeled and their performances comp ared, one based on cone emitters (CE) and the other based on wedge emi tters (WE). The emitters have parabolic shape. The CE and WE structure basal areas are chosen to be the same, allowing extension of the resu lts to GFED and FEMT arrays. The planar Fowler-Nordheim (FN) current d ensity-electric field J(E) relationship is assumed to be valid. The cu rrent I is obtained by integration of J over the emitter's surface. No ''field enhancement'' and ''area'' factors are used. The two-dimensio nal Laplace equation for the electric potential is solved numerically using a Gauss-Seidel iterative procedure, having as special features: appropriate coordinate systems; a unique lattice for both CE and WE mo deling; lattice steps in both directions in geometrical progression; e mitters described by lattice points lying on it. The GFED model parame ters are: emitter curvature radius R, height h and work function phi, together with the gated anode circular aperture radius r, height H and gate voltage V(g). Besides these parameters, the FEMT model includes also as parameters the anode height D and the anode voltage V(a). GFED - and FEMT-obtained simulation results refer to the effect of model pa rameters on the emission current. FEMT modeling results also include t ransconductance, base resistance, gain, capacitance and cut-off freque ncy. Several device design suggestions are drawn.