A study of a resonant condition of symmetric triple-barrier structures by using circuit theory

Abstract

Recently, quantum effect devices have been studied extensively and new functional devices not observed in the conventional devices are expected. As a result, the necessity of developing a design method for superlattices is enhanced. The authors have proposed a method in which the multiple barrier structures are replaced with complex equivalent circuits. Using this method, it is now possible to treat the resonant tunneling effect from the viewpoint of circuit theory. It was shown that the network synthesis theory can be applied to the design of the superlattice. Although the resonant tunneling effect of a double-barrier structure has been studied extensively for device applications, little attention has been given to the triple-barrier structures. In this paper, numerical experiments are carried out with this complex-valued equivalent circuit model so that the resonant conditions of the symmetric triple barrier are studied. To this end, the matching condition valid for a circuit symmetric right to left is applied to the equivalent circuit of a symmetric triple-barrier structure so that its resonant condition is investigated. It is found that the electron energy that makes the impedance viewed at the center of the equivalent circuit purely resistive is the complete resonant level. It is shown also that this resonant condition can be understood easily by the use of the Smith chart.