Semiconductor-metal transition in a square quantum wire system

Semiconductor-metal transition in a square quantum wire of the GaAs/GaAlAs system is investigated 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 7 nm. Critical impurity concentrations at which the transition occurs increase with reduction in well width. The effects of Anderson localization and correlation in the Hubbard model are included in a simple way. In general, the critical concentration is one order higher in the square quantum wire system when compared to a quantum well case for lower well widths. When well width is increased it reaches the bulk value in both the cases. The critical concentration is enhanced when a random distribution of impurities is considered. © 2002 Elsevier Science B.V. All rights reserved.