Metal-semiconductor structures based on composite semiconductors A1B5C6 are investigated as possible γ-ray detectors. Electric measurements carried out on the samples before the irradiation have exhibited no special peculiarities. After irradiation the analogous investigations have shown dramatic changes of charge carriers transport. Numerical analysis showed the field-current characteristics similar to the p-n-homo-junction: the forward current is described by the power law I∼(Fa)3/2, where Fa stands for applied electric field. Under reverse bias two clear modes of the carriers transport are observed: under the so-called threshold field FTR ∼ 300 V/m the experimental current is governed by quasi-ohmic law I∼(Fa)0.8; as the applied field exceeds the threshold value, the field-current dependence points out the strong trap-assistant tunneling processes: I∼(Fa)5.