Аннотация:Pb1-xSnTe(In)(x = 0.20) MBE films have been prepared on BaF2 substrates. The characteristics of resistivity relaxation under the combined effect of a pulsed electric field and IR illumination have been investigated. We have shown that the films can be used as rather fast-response photodetectors operating in a regime of periodic accumulation and quenching of the signal.