Localization of Electrons in Structurally Disordered Lattices

The localization of electrons in structurally disordered lattice is investigated by following Anderson's probabilistic approach. Based on the cell model, the strong dispersion of transfer energy due to fluctuations in the interatomic distance is transformed into the fluctuations in the molecular levels of the cells. The energy dependence of the critical value W / V for the electron localization is studied in the low energy tail in the spectrum of a cell system, with average intercell transfer energy V , by considering the distribution with width W of energies of only lowest bonding states of molecules. The critical value is found to decrease drastically with the decrease of distribution function of molecular levels. This behavior will confirm the conjecture that, in doped semiconductors, the electronic states are strongly localized in the tail of the impurity band or in the tailing region of the main band in heavily doped systems.