The temperature dependence of interface characteristics in An/GaP contact system has been studied by X-ray diffraction (XRD) and scanning electron microscope (SEM).The measurements show that even at temperature below 400C the interface reaction will form a little amount of An-Ga inter-metallic compound. Its main constituents are (GaAu)H

Ga

2

Au. In the case of alloying at a higher temperature 550C the surface of GaP compound has decomposed. The interface reaction is enhanced accompanying by rapid atomic inter-diffusion. Extensive out-migration of gallium atoms into gold film overlay and penetration of gold atoms into the GaP layer have been observed. The chemical reaction between An-Ga occurs and form (GaAu)H

Ga

2

Au and (GaAu)8O etc.These experimental results suggest that the interface between the An layer and GaP is a metal-semiconductor interfacial reaction and alloying re-growth layer

which contains An

Ga and P atoms. The An-Ga inter-metallic compounds can contribute to the improvement of mechanical strength and the adhesion of An film. The SEM observation indicafes that as alloying temperature exceeds the An-Ga eutectic temperature 470C

the surface morphology of M-S contact becomes rougher and more inhomogeneous.With rising the temperapture

the microcrystal grains of interface layer become larger.At 600℃

the micro-crystallization effect is obvious. In fact

the alloying condition is not favorable to the of ohmic contact fabrication.