In order to interpret the effect of Co-60 gamma-ray irradiation dose on the electrical characteristics of MIS Schottky diodes, they were stressed with a zero bias at 1 MHz in dark and room temperature during gamma-ray irradiation and the total dose range was 0-450 kGy. The effect of gamma-ray exposure on the electrical characteristics of MIS Schottky diodes has been investigated using C-V and G/omega-V measurements at room temperature. Experimental results show that gamma-ray irradiation induces a decrease in the barrier height Phi(B) and series resistance R-s, decreasing with increasing dose rate. Also, the acceptor concentration N-A increases with increasing radiation dose. The C-V characteristics prove that there is a reaction for extra recombination centers in case of MIS Schottky diodes exposed to gamma-ray radiation. Furthermore, the density of interface states N-ss by Hill-Coleman method increases with increasing radiation dose. Experimental results indicate that the interface-trap formation at high irradiation dose is reduced due to positive charge build-up in the Si/SiO2 interface (due to the trapping of holes) that reduces the flow rate of subsequent holes and protons from the bulk of the insulator to the Si/SiO2 interface. (c) 2006 Elsevier B.V. All rights reserved.