The p-GaAs

p-InP are the cap layer material of the photoelectronic devices. The influence of the characteristics of p-electrode on the parameter of the LED with Cr/Au or Au-Zn alloy p-electrode contact material have been studied. The investigation of the interface between the p-GaAs

p-InP and contact metal

and electrical characteristics is important for improving parameters of the devices and their reliability. In this work

the Zn diffused GaAs and Zn doped single-crystal InP polished wafers were used as the starting material. The small pieces of the sample were placed into evaporator equipment. The samples were processed by the vacuum-evaporating Cr 500Å

Au 3000Å

then the samples heat-treated at 450℃ for 5 min in pure nitrogen atmosphere.The surface morphology of the samples after heat treatment was observed by SEM. The effect of alloy temperature on the specific contact resistance (

ρ

c

) was studied. The interdiffusion of p-GaAs/Cr/Au and p-InP/Cr/Au at interface has also been investigated by AES.It was found that the interdiffusion of Au does not occur during the heat treatment of p-GaAs/Cr/Au system. The Cr layer as a diffusion barrier plays an important role

ρ

c

=6-8×10

-5

Ω·cm

2

. The Cr/Au layers are used as pelectrode for GaAs/GaAlAs DH LED. The

I-V

characteristics of the devices do not change after 5×10

3

hours CW operation at

I

f

=100mA condition. The results indicated that the p-GaAs/Cr/Au system has good stability.Interdiffusion of Au

In and P occurs during the evaporation

therefore

p-InP/Cr/Au system is not a good p-electrode material for the p-InP/InGaAsP devices.