  The methods of non-equilibrium thermodynamics of systems with an interface
have been applied to the study of thermionic emission processes in abrupt
semiconductor junctions, including the effects of surface states . Our analysis
covers different situations of interest, concerning unipolar and bipolar
systems, either degenerate or not, with or without interface states and under
steady and non-steady conditions. In this way, a complete phenomenological
modelling of thermionic emission-interface states processes has been proposed,
overcoming some of the inherent limititations of the currently existing models.
