Effects of variational parameter in the study of metal-insulator transition in a quasi-two dimensional semiconductor system

摘要

Effects of variational parameters on different dielectric functions in the study of semiconductor-metal transition are investigated for a shallow donor in an isolated well of GaAs/Ga1-xAlsAs superlattice system within the effective mass approximation. Vanishing of the donor ionization energy as a function of well width and donor concentration suggests that no transition is possible below a well width of 30 Angstrom supporting the scaling theory of localization. The effects of Anderson localization, exchange and correlation in the Hubbard model axe included in a simple way. The relationship between the present model and the Mott criterion in terms of Hubbard model is also brought out. The critical concentration is enhanced when the Hartree-Fock dielectric function is used. Results are compared with the existing data available and discussed in the light of existing literature. [References: 31]