The relation between alloying temperature and specific contact resistivity in the Au-Zn/Au-Sb/GaP system has been reported. At alloying temperature of 520℃-560℃. good ohmic contact characteristic has been obtained. By observing the small islands in the interface of the contact system using scanning electronic microscope

energy dispersive spectrum and Auger energy spectrum

we have found that the ohmic characteristic has a close relation with the formation

size and density of the small islands. Analysing theorectically the relation between small islands and the specific contact resistivity

we have explained the facts that small and dense islands can result in a low specific contact resistivity

and we also proposed a mi-crostructure model which shows good ohmic contact behavior of Au-Zn/Au-Sb/GaP system.