Terahertz Sensitivity of Pb_1-xSn_xTe:In

Abstract

An increase in the electric current through Pb 1 − x Sn x Te:In exposed to laser radiation with a wavelength of λ = 336.8 μ m was observed. The effect can be explained on the assumption that the low-frequency permittivity ϵ of Pb 1 − x Sn x Te:In increases under illumination due to photon absorption resulting in the production of one or, more likely, two phonons near the center of the Brillouin zone on the branch responsible for the ferroelectric phase transition. In turn, the increase in ϵ leads to an increase in the electric current, identified as an injection current, known to vary in proportion to ϵ.