Shell-filling effects and Coulomb degeneracy in planar quantum-dot structures

Abstract

We investigate the influence of electron-electron interactions on the electronic properties of quantum dots in a regime where the energy-level separation is comparable to or larger than the Coulomb charging energy at low temperature (e(2)/2C much greater than k(B)T). A self-consistent three-dimensional solution of Schrodinger and Poisson equation within the local-density approximation is implemented to study the formation of shell structure in highly symmetric quantum dots which is in good agreement with recent experimental results [Tarucha et al., Phys. Rev. Lett. 77, 3613 (1996)]. For asymmetric quantum dots, we show that the shell structure disappears, and features due to electron-electron interaction lead to the accidental formation of an isolated electron shell called "Coulomb degeneracy" in the energy spectrum. [S0163-1829(97)02648-9].