Coherent electron flow from a double slit with slit widths in the quantum conductance regime

We report on a theoretical study of the quantum interference behaviour of electron flow from a double-slit device made from a semiconductor two-dimensional electron gas (2DEG) system with the slit widths in the quantum conductance regime. The device consists of a double slit and a single slit in a configuration where the single slit is placed on the source side of the double slit. The wavefunctions of electrons passing through the double-slit structure are calculated on the basis of a scattering matrix method. It is found that including a single slit between the double slit and the source contact in the device is essential for the observation of interference fringes of electron flow in a double-slit experiment with a 2DEG. When only the lowest mode is open for conduction in the individual slits, the interference patterns of electron flow from the double slit resemble the results of a conventional Young's double-slit experiment well. When several modes are open for conduction in the individual slits, the interference patterns of electron flow from the double slit are dominated by the interference of electrons flowing through the highest index open modes in the slits. As a result of the existence of multiple-lobe structures in electron flow from these high index open modes, these interference patterns, in general, show rather complex structures. We also discuss the characteristics of interference patterns in the near-and far-field regimes and the dependence of the fringe spacing on the slit distance in the double slit