Bistable amphoteric centers with reverse order of electron levels in semiconductors

The effect of bistability of amphoteric centers with negative correlation energy on the free-carrier concentration is studied. It is found that, in the absence of doping compensation, in a certain temperature range, the free-carrier concentration does not depend on the concentration of bistable amphoteric U ^? centers. The conductivity activation energy and the Fermi level position in the band gap of the semiconductor are determined not only by the electronic characteristics of the centers, such as the center ionization energy, but also by the parameters of transitions between the two equilibrium states of the center. The results of the simulation of the temperature dependence of the free-carrier concentration in a semiconductor with bistable amphoteric U ^? centers are presented for different levels of compensations. It is shown that the observed activation energy of the dark conductivity depends on the compensation degree.