It is well known that the exposure of any semiconductor surfaces to the Co-60 gamma-ray irradiation causes electrically active defects. To investigate the effect of gamma-ray irradiation dose on the electrical characteristics of metal-insulator-semiconductor (MIS) Schottky diodes, the fabricated devices were exposed to 7 radiation at a dose of 2.12kGy/h. The total dose range was from 0 to 450kGy at room temperature. The density of interface states N-ss as a function of E-ss-E-v, the values of series. resistance R, and the bias dependence of the effective barrier height 0, for each dose were obtained from the forward bias I-V characteristics. Experimental results show that the gamma-irradiation gives rise to an increase in the zero bias barrier height Phi(BO), as the ideality factor n, R-s and N-ss decreases with increasing radiation dose. (c) 2006 Elsevier B.V. All rights reserved.