New physical formulation of the thermionic emission current at the heterojunction interface

The thermionic emission current for electrons across the heterojunction interface is classically modeled as the difference between two opposing electron fluxes. A new, consistent, physical model, which includes the carrier degeneracy and nonideal behavior effects, is presented. It is shown that the emission current at the interface can be expressed in a simple closed-form formalism that gives the relationships among the average directional thermal velocity of electrons, the conduction band discontinuity, and the carrier activities at both sides of the interface. The conditions under which the thermionic emission occurs at the heterointerface are discussed.<>