CONSEQUENCES OF SPATIAL DISTRIBUTIONS OF THE INTERFACE STATES ON THE SCHOTTKY-BARRIER

In this paper we study, by numerical simulations as well as by asymptotic expressions, the behavior of Schottky barriers correlative with the distribution of the interface states. These interface states are assumed to be discrete in energy and have a density decreasing exponentially to the semiconductor bulk. First we calculate the shape of the potential near the semiconductor surface. Then, from a definition of the "effective" barrier height and the surface potential of the semiconductor, we determine the relation ΦB(ΦM) and specify quantitatively the conditions of the stabilization of ΦB. We simulate at first the case of one level, because it permits to emphasize clearly the role of the parameters of the interface states (energy level, density, penetration depth, nature) and of the materials (dopant, metal work function etc). Then we extend the discussion to more than one level. We show that a curve ΦB(ΦM) can be built by making use of asymptotic diagrams of the penetration depths of the states do not exceed ∼ 10 A ̊. Some examples of simulation are given to indicate the complexity of barrier shapes in the case of deep extension of interface states. Finally, we compare the curves ΦB(ΦM) of simulation with experimental results available for Si, GaAs and InP. © 1990.