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We have compared directly the performance of a Pb1−xSnxTe(In) photodetector with that of two other state-of-the-art far-infrared detectors: a Si(Sb) blocked impurity band (BIB) detector and a Ge(Ga) photoconductor in an integrating cavity. The Pb1−xSnxTe(In) photodetector has current responsivity SI several orders of magnitude higher than the Si(Sb) BIB at wavelength λ=14.5 μm. Persistent photoresponse with SI∼103 A/W at 40 mV bias and 1 s integration time at the wavelengths λ=90 and 116 μm has also been observed in the Pb1−xSnxTe(In) photodetector. This is larger by a factor of ∼100 than the responsivity of the Ge(Ga) photoconductor in the same conditions.

We present Raman spectra and results of galvanomagnetic measurements of PbTe single crystals, doped with gallium, between 10 and 300 K. The effect of persistent photoconductivity depends on the gallium concentration. In all samples well-resolved peaks were observed at about 104 cm-1 (impurity-induced PbTe LO mode) and 166 cm-1 at all temperatures. Another mode appears at about 117 cm-1 at temperature below 250 K. One additional mode, at about 188 cm-1, is observed in PbTe + 0.4 at% Ga. These modes are discussed in terms of local vibrations of impurities corresponding to different Ga charge states.

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