Photoconductivity of the narrow-gap Pb1 − xSnxTe(In) semiconductors in the terahertz spectral range

The spectral dependence of photoconductivity in the doped narrow-gap semiconductor Pb0.75Sn0.25Te(In) under the action of terahertz laser radiation pulses has been studied at temperatures 4.2–30 K. It is shown that the photoconductivity spectrum of the semiconductor spreads at least up to the wavelength of 500 μm. This value is more than twice higher than the red cutoff wavelength of 220 μm in uniaxially stressed Ge(Ga) which is known as the most long-wavelength photodetector among sensitive photon detectors of radiation. Mechanisms responsible for photosensitivity of PbSnTe(In) in the terahertz spectral range are discussed.