In this research, we have investigated the electrical properties of metal-semiconductor (Sn/p-Si) Schottky barrier diodes (SBDs) under Co-60 gamma (T)-rays. These devices is stressed with a zero-bias during Co-60 gamma-ray source irradiation with the dose rate 2.12 kGy/h and total dose range was 0-500kGy at room temperature. Electrical measurements of Sn/p-Si SBDs have been performed using current-voltage (I-P) and capacitance-voltage (C-V) techniques. Experimental results show that gamma-irradiation induces an increase in the barrier height Ob(C-P) obtained from reverse-bias C-V measurements with increasing dose rate. However, the barrier height Phi(b)(I-V) obtained from forward-bias I-V measurements remained almost 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. On the other hand, the values of the ideality factor obtained from I-V measurements increased with increasing dose rate. The results show that the main effect of the radiation is the generation of laterally inhomogeneous defects near the semiconductor surface. (c) 2006 Elsevier B.V. All rights reserved.