Surface-wave amplification between parallel semiconductors

In the parallel arrangement of two slabs of semiconductors incorporating drifting carriers, dispersion equations governing surface-wave propagation are derived. The wave is a space-charge wave along the interface. It can be the polarization wave utilizing minority carriers. The relation is deduced from a set of transport equations and boundary conditions. The dielectric relaxation frequency, which represents the attenuation coefficient in the usual theory, becomes negative and promotes the growing of the interface wave when the relative drift velocities of carriers in two semiconductors are in a special condition. It is a result of interaction due to field penetration between parallel semiconductors of nonequal material properties which are mutually translating. The Debye length and the "unsymmetrical material property" effect are Considered as the important factor. The dispersion equations are compared with the one-dimensional analysis to show a difference in the physical interpretation.