In order to interpret the effect of (CO)-C-60 gamma-ray radiation dose on the electrical characteristics of metal-semiconductor (Au/n-GaAs) Schottky barrier diodes (SBDs), these devices were stressed with a zero bias during 60CO gamma-ray source irradiation with the dose rate 2.12 kGy h(-1) and the total dose range was 0-500 kGy at room temperature. Experimental results show that gamma-irradiation induces an increase in the barrier height Phi(b)(C-V) obtained from reverse-bias C V measurements, whereas barrier height Phi(b)(I-V) obtained from forward-bias I-V measurements remained essentially constant. This negligible change of Phi(b)(I-V) is attributed to the low barrier height in regions associated with the surface termination of dislocations. The experimental I-V and C-V characteristics prove that there is a reaction for extra recombination centers in case of SBDs exposed to gamma-ray radiation. Also, the ideality factor n and donor concentration decrease with increasing dose rate. Both I-V and C-V characteristics of the Schottky diode indicate that the total dose radiation hardness of GaAs devices may be limited by the susceptibility of the Au-GaAs interface to radiation-induced damage. The density of interface states N-SS distribution profiles as a function E-CC-E-SS for each dose rate was extracted from the forward-bias I-V characteristics taking into account the bias dependence of the effective barrier height Phi(e), at room temperature. N-SS decreases with increasing dose rate and above 250 kGy it remains constant. Such a behavior of N-SS is attributed to the existence of the native insulator layer between the metal and semiconductor that passivates the surface of semiconductor, and thus the increase of the N-SS. (c) 2005 Elsevier B.V. All rights reserved.