A THEORETICAL MODEL FOR DESCRIPTION OF WORK FUNCTION LOWERING FOR SEMICONDUCTOR / INSULATOR UNDER THE INFLUENCE OF THE CHARGED BILAYER IN THE SURFACE REGION

We develop a simple theoretical model, connecting a  lowering of the electron affinity of a semiconductor  (or insulator) with such parameters as the density of  surface charge, localized on surface states or  adsorbed atoms, and the volume density of charge  within the space charge region, both of which form a charged bilayer on the surface. Our model allows to estimate the perspectiveness of various materials as films for creating modern photocathodes or effective field emission cathodes with substantially lowered or zero work function.