Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10642360 | Physica E: Low-dimensional Systems and Nanostructures | 2005 | 6 Pages |
Abstract
Metal-Insulator transition using an exact two-dimensional (2D) dielectric function is investigated for a shallow donor in an isolated well of a GaAs/Ga1âxAlsAs superlattice system within the effective mass approximation. Vanishing of the donor ionization energy as a function of well width and the donor concentration suggests that a phase transition is not possible even below a well width of 10Â Ã
, supporting the scaling theory of localization. The effects of Anderson localization, exchange and correlation in the Hubbard model are 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 appears to be enhanced when a random distribution of impurities is considered. The limiting behaviour of the well width for a quantum 2D well is brought out. A simple expression is derived for a Mott constant in 2D, a*Nc1/2 exp (9.86 exp (âL/a*))=0.123, where Nc is the critical concentration per area. Results are compared with the existing data available and discussed in the light of existing literature.
Related Topics
Physical Sciences and Engineering
Materials Science
Electronic, Optical and Magnetic Materials
Authors
A. John Peter,