Shallow traps and the space-charged-induced limitation of the injection current in PbSnTe:In narrow-gap ferroelectric

In the present paper, for the first time the energy spectrum of localized states in PbSnTe:In was obtained by analyzing experimental current-voltage characteristics of PbSnTe:In film samples measured at T=4.2 K under conditions with prevailing injection of charge carriers out of contacts. The sensitivity of PbSnTe:In to submillimeter radiation due to localized states was calculated versus the radiation wavelength and the bias voltage. The calculated values were compared to experimental data obtained upon illumination of PbSnTe:In samples with free-electron laser radiation with wavelengths λ=130 and 198 μm.