EQUIVALENT NETWORK APPROACH FOR MULTISTEP DISCONTINUITIES IN ELECTRON WAVE-GUIDES

An analysis method is described for multistep discontinuities in electron waveguides composed of semiconductor heterostructures. The method is based on a rigorous mode-matching procedure that takes into account the effects of external finite potential and spatially varying effective mass. Stress is placed on network representations to establish physical pictures of the quantum effects and to yield insight; in addition, a systematic microwave network approach is employed. The equivalent network representation is given for the waveguide modes propagating normally to the step discontinuity, and the mode-matching procedure is described for the boundary-value problem of the step discontinuity. Combining the above two procedures, the super-cascade matrix formulation is carried out, from which the reflection and transmission characteristics of multistep discontinuities in electron waveguides can be estimated. In order to show the validity and usefulness of this approach, examples are computed for constriction structures composed of three-layered electron waveguides.