Interplay between quantum confinement and electron-electron interaction in deformed silicon quantum wires

In this paper we investigate quantum confinement and electron-electron correlation in silicon deformed quantum wires. Starting from the single-particle picture, which shows the possibility of localizing one electron inside the wire deformation, we build a variational ansatz for the two-electron ground state. We compare the localizing effect induced by the deformation with the Coulomb repulsion, pointing out the existence of a two-electron confined ground state, depending on the wire geometry. On varying the geometrical parameters characterizing the wire deformation, it is possible to switch from structures dominated by the localization to structures in which the increase of the available volume makes the Coulomb contribution very relevant, as for ordinary quantum dots. The effects induced by the dielectric mismatch between the wire and the surrounding medium are included and discussed.