PECULIARITIES OF TRANSPORT-PROPERTIES IN SEMICONDUCTORS WITH RESONANTIMPURITIES - HGSE-FE VERSUS PBTE-CR

We compare the transport properties of two semiconducting systems cont aining resonant donors, HgSe:Fe and PbTe:Cr, with concentrations of do pants corresponding to the Fermi level being stabilized at the resonan t state. It is known that under such conditions, at a low temperature, there arises a spatial correlation of electric charges localized on d onor centers. The occurrence of the correlation is driven by the inter -donor Coulomb repulsive interaction. In the case of HgSe:Fe, the corr elation leads to a sizable enhancement of the conduction electron mobi lity. In the case of PbTe:Cr, high values of the dielectric constant l imit the temperature region in which the correlation is expected to oc cur, to temperatures below approximately 3.5 K. Therefore, no direct o bservation of the mobility enhancement was possible. On the other hand , a lack of a strong suppression of the mobility by the resonant scatt ering mechanism can be taken as an indirect indication that the positi ons of charged donor centers are correlated to such an extent that for mation of the Coulomb gap (due to inter-donor Coulomb repulsive intera ction) causes the resonant scattering to be very inefficient.