FIELD-EMISSION DIODE CHARACTERIZATION THROUGH MODEL PARAMETERS EXTRACTION FROM CURRENT-VOLTAGE EXPERIMENTAL-DATA

Standard field emission diode and array modeling is based on the planar Fowler-Nordheim (FN) current density-electric field J(E) relationship and the introduction of the field enhancement a and area b factors to relate E and J to the measurable quantities potential V and current I. This approach is questionable because E is not constant on the emitter and the b factor is V dependent. In this article, while still using the FN J(E) relationship. I(V) is obtained through J integration over the emitter surface, based on the ideal field emitter floating sphere model (FSM). The model parameters are the emitter's height h, radius R, work function phi, and anode-cathode planes spacing d and the factors a and b are not used. A parameters extraction procedure (PEP) has been developed, in order to obtain the value of the parameters within the model framework ensuring the best fit to the experimental field emission data. The objective function to be minimized is the standard deviation between FSM and experimental field emission I(V) data. The nonlinear minimization routine used in PEP has been chosen after an extensive testing. The best set of searching variables is outlined. The PEP was applied to reported field emission data. An electric field reduction factor rho was introduced allowing a physical explanation to be derived. Several ways of applying the PEP are suggested.