EFFECT OF AN IMPURITY IN THE WIDE-NARROW-WIDE QUANTUM WAVEGUIDE STRUCTURE

Abstract

We present a numerical study of the influence of junction-geometries and disorder on quantum-mechanical transmission by considering the presence of an impurity in a wide-narrow-wide (W-N-W) quantum-wire junction. The device is modeled as an electron waveguide of finite cross section. Transmission and reflection probabilities as well as conductance are computed by using model expansions of the wave function together with a waveguide-matching technique. The calculations show that the transmission of the two-dimensional electron gas through the W-N-W geometry is highly sensitive to geometries of junction and can be suppressed by the presence of a repulsive or attractive impurity potential. Furthermore, the depression effect becomes more visible if the absolute value of potential strength becomes bigger.