Impurity Potential Constraints In The Quantum Dot Electronic Structure Of Few-body System

Quantum dots are nanoscale electronic objects, typically fabricated using two dimensional semiconductor heterostructures. In addition to promising technological applications, quantum dots represent excellent sources of interesting many-electron quantum physics.The applied magnetic field can control the electron-electron interaction by tuning the average distance between the electrons. Whe the dimension of the system is lowered, the donor can hold two electrons due to the increasing binding energy. Being the simplest unsovable many-body system, the D~- system in non-circular quantum dot offers a good opportunity to study the influences from both the confinement from quantum dot and magnetic filed on electron-electron interaction and electron-impurity interaction.In this paper, we report on a theoretical study of a D~- system in a non-circular GaAs quantum dot by an exact diagonalization method. The stability diagram of the D~- center against the position of the donor is obtained in the presence of perpendicular magnetic fields. At zero magnetic field, it is found that the D~- center would disintegrate if the donor is too close to the edge of the dot. In a finite field, the system is always binding when the donor is localized in the center of the dot. As the donor moves away from the center to the edge, it is seen that the magnetic field can cause the disintegration of the system. The result clearly reveals the interplay between the electron-electron interaction, quantum confinement, and external magnetic fields.