Multi-layered Pd/Zn/Pd metallic films to form good ohmic contacts with p-type GaP have been reported.From the analysis of Auger electron spectroscopy(AES)

it is concluded that

at 550℃ for 3min

tho optimum alloying process

P and Ga atoms move to metal layers from GaP surface

Pd atoms diffuse into interface layer

and Zn atoms diffuse into GsP substrate as well as out layer. Jn alloying process. Pd is found to play an important role in forming ohmic contact for Zn to be doped into GaP. Pd reacts with Ga and provides good wetting for Zn to adhere to the surface of GaP and the Ga sites are occupied by Zn

Zn atoms are acceptors when they occupy Ga sites in GaP and increase the carrier concentrations in GaP to form a high concentration p

++

layer. So the contact interface has M-p

++

-p structure and the ohmic contact resistance is greatly lowered.From analysis of secondary ion mass spectroscopy (SIMS) combined with X-ray diffraction(XRD)measurments it is concluded that there are ZnP

+

GaP

+

ZnP

2+

PdP

+

Gat and PdZn

+

ions in contact interface. The metallurgical phases of these complex ions are ZnP

2

GaP

Zn

3

P

2

Pd

8

P and(Ga

4

Pd

7

Zn

3

)

14

k in metal-semiconductor(M-S)contact layer. As a result

the

M-S

contact area is increased and the ohmic contact resistance for Pd/Zn/Pd structure system to p-type GaP is decreased.