WEAK AND STRONG LOCALIZATION IN LOW-DIMENSIONAL SEMICONDUCTOR STRUCTURES

The dependence of the localization length on the number of occupied su bbands N in low-dimensional semiconductors is investigated. The locali zation length is shown to be proportional to the number of occupied su bbands in quasi-one-dimensional quantum wires, while it grows exponent ially with N in quasi-two-dimensional systems. Also, a weak localizati on theory is developed for large N with a well-defined small expansion parameter 1/N. The temperature dependence of the conductivity deduced using this perturbation theory agrees with the experimentally observe d dependence.