ABSTRACT
Doping of the lead telluride and related alloys with the group III impurities results in appearance of unique physical features, such as Fermi-level pinning, persistent photoconductivity and others that are not typical for undoped material. This is explained by appearance of a barrier between local and extended states that does not allow electrons to recombine to the initial local state after excitation by illumination. It is known that there is a possibility to quench the conductivity to the initial “dark” state by applying high frequency electric field to the sample, but no reasonable explanation to this phenomenon has been made before. We have studied influence of high frequency electric field on conductivity of Pb0.75Sn0.25Te(In). DC conductivity measurements were done at helium temperatures in persistent photoconductivity regime while “pumping” electric field with frequencies 50 - 650 MHz applied. It was found that there is a strong dependence of DC conductivity of studied samples on frequency of “pumping” electric field with a peak at about 350 MHz. Position of this peak does not depend on the applied electric field. The peak amplitude depends on bias applied across the sample. Possible mechanisms of these phenomena are discussed.
