Metal-insulator transition in a quantum well under the influence of electric field

Ionization energies and the polarizabilites of a shallow donor in a quantum well of the GaAs/Ga1−xAlxAs superlattice system are obtained. In the presence of an electric field, a variational procedure within the effective mass approximation is employed. Within the one-electron approximation the occurrence of Mott transition is seen when the binding energy of a donor vanishes. The effects of Anderson localization and exchange and correlation in the Hubbard model are included in our model. It is found that the ionization energy (i) decreases as well width increases for a given electric field, (ii) decreases when well width increases, and (iii) the critical concentration at which the metal-insulator transition occurs is reduced in an external electric field. All the calculations have been carried out with finite and infinite barriers and the results are compared with available data in the literature.