ИСТИНА

In order to elucidate effect of Fe impurity on the galvanomagnetic properties of PbTe and obtain information on the Fe impurity states in this semiconductor we investigated the temperature dependencies of resistivity and Hall coefficient in Pb1-yFeyTe alloys in the weak magnetic fields (T=4.2-300 K, B<0.07 T). It is found that in all samples temperature dependencies of resistivity and Hall coefficient have a metal-like character. The free hole concentration at T=4.2 K decreases with the increase of iron content and reaches saturation at p=(7-8)∙1017 cm-3 in the interval of iron concentration y=0.005-0.012. In the same range of Fe content Hall coefficient RH changes in specific manner: it increases by approximately ten times and passes through a maximum with increasing temperature. It indicates the pinning of Fermi level by the resonant impurity level located on the background of the valence band. However following doping (y>0.015) leads to the p-n-inversion of the conductivity type and monotonous increase in the free electron concentration. In the frame of the six-band Dimmock’s dispersion relation calculation of dependencies of the Fermi level and the free charge carrier concentration on the iron content was performed and position of the Fe-induced resonant impurity level relative to the valence band top was determined.