ELECTRICAL-CONDUCTION IN SEMICONDUCTOR JUNCTIONS WITH INTERFACE DIPOLE LAYERS

We have studied the steady-state dc and small-signal ac conduction in semiconductor junctions with interface dipoles. The junctions have bee n modeled according to the two experimental methods used to fabricate these structures. In the first method, Si or Ge atomic layers are depo sited at the interface of a III-V junction; in the second, a closely s paced pair of delta doping layers, one n type and one p type are inser ted in the growth process. The numerical study is based on the resolut ion of Poisson's equation and of the continuity equation for electrons and holes. It yields the energy band diagrams, the steady state and a c components of the carrier concentrations and current densities as fu nction of position. In particular, it is shown for the case of junctio ns with delta-doped interface dipoles that the modulation of the ioniz ed dopant concentrations in the Slayers leads to a significant contrib ution to the total capacitance. As final results, the current-voltage I(V) and capacitance-voltage characteristics C(V) are obtained. Compar ison of the I(V) curves with existing experimental data shows good agr eement. The analysis of the C-2(V) curve as function of V yields a met hod to determine the existence and the strength of the interface dipol e. (C) 1996 American Institute of Physics.