Local order of Te impurity atoms in heavily doped GaAs:Te and accompanying electron localization effect

摘要

We show the results of joined studies of the free electron concentration and x-ray diffuse scattering from heavily doped GaAs:Te single crystal as a function of controlled annealings at high temperatures 700-1200°C and Te concentration 10{sup}18-2×10{sup}19 cm{sup}(-3) from the range, where the free electron concentration saturates. Changes of electron concentration caused by annealings are accompanied by structural changes, both being in a high coincidence and reversible versus annealing temperature. On a basis of the microscopic model of x-ray diffuse scattering from a solid solution, newly proposed here, we argue that impurity atom pairs arise, locally in a crystal, when the free electron concentration is lowered by annealing. We suppose that the electron localization is caused by impurity atom pairs, supporting recently published results.