Semianalytical model of electron source potential barriers

Potential barrier profiles are developed for the study of field and thermio nic emission electron sources. The model consists of the exchange and corre lation potential, an ionic core potential to correct the ''jellium'' model, a triangular representation of the barrier, and a numerical integration of Poisson's equation to evaluate the dipole potential. As a test, evaluation s of the work function of various metals are made which rely on "effective' ' ionic radii which are often close to the actual ionic radii, and a good c orrespondence is found between the potential profiles and an "analytic" ima ge charge potential. Modifications to the parameters inherent in the Richar dson-Laue-Dushman and Fowler-Nordheim equations, so as to obtain current de nsity estimates, are described. The method is suggested to be suitable for the analysis of more complex potential barrier profiles which are encounter ed in actual (realistic) thermionic and field emission electron sources, in that it captures the behavior of the exchange-correlation potential near t he surface and includes those effects in the image charge potential. [S0734 -211X(99)00302-9].