We have calculated the conductance of a two-dimensional electron gas through single and double constrictions using a mode-matching technique. In order to take into account the smooth variation of the confinement potential, and the presence of disorder, the calculation is made within a lattice model. We find that the conductance at plateaus is reduced below the quantized values if short-range scatterers are introduced in the channel. However, the conductance remains well quantized even in the presence of long-range impurities. These observations explain the suppression of conductance time-dependent fluctuations at plateaus experimentally observed by Timp et al. [Phys. Rev. B 42, 9259 (1990)]. We also examine the effects of impurities on the resonant transmission properties through a single quantum dot. As the disorder is introduced, the resonances are broadened in energy and can appear as either peaks or dips depending on the strength of the disorder.
ASJC Scopus subject areas
- Condensed Matter Physics