1 the injection-induced impuriQ photoconductivity (IIIP)in specially undoped InSe single crystals was explained on the basis of the existence of uncontrollable impurity centres, i. e. trapping levels in the forbidden gap of this material and their non-uniform distribution along the specimen. In order to refine the details of this model, the present report deals with an investigation of the effect of doping on the llIP in the above semiconductor. Specilnens with thicknesses from 3 0 to 200 pm were obtained by spallation from large 1nSe:Gd single crystals with NGd = 0.10, 0.20, 0.30, and 0.40 a%, grown by the Bridg -38, 29 (1982).

In I1 to 41 the effect of specially doped gadolinium impurities on the photoelectrical properties of indium selenide single crystals has been reported. The present note deals with the influence of Gd doping on the switching effect in the given material.The samples studied were grown by the Bridgman method and were cut from large n-1nSe:Gd single crystalline boules with Gd concentration NGd = 0.00, 0.10, 0.20, 0.30, 0.40 at%. The Gd impurity was doped into the material during synthesis. The In, Sn, Ag, or aquadag contacts have been located so that the current passes along the C axis of the crystals. l ) P. Lumumba Str. 23, SU-370073 Baku, USSR