The influence of thermal ionization of an impurity delta-doped layer situated either in the center or on the edge of a quantum well (QW) on impurity binding energy is investigated theoretically for the case of Si0.8Ge0.2/Si QW. It is shown that the Hartree potential created by free electrons and by ionized impurities at high temperatures superimposes on the original (at low temperature) QW energy profile. Resulting new QWs have their own impurity binding energies. It is of interest that energies are nearly the same for center- and edge-doped QWs, contrary to those at low temperatures. The obtained results are explained on the basis of Coulomb’s law when decreasing the mean distance between free electron and impurity atom with temperature involves an increase in the impurity binding energy.

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