ANOMALOUS LATERAL ZN SURFACE-DIFFUSION IN INP CAUSED BY ZN-CONTAINED METALLIZATION

We report an anomalous Zn surface diffusion in InP during annealing of ohmic contact structures containing Zn. A Pd/Zn/Pd contact was used t o demonstrate this phenomenon. Electrical properties of the contact we re monitored to corroborate this anomalous surface diffusion. Cross-se ctional scanning electron microscopy was also used to delineate the Zn diffusion front lines. It was found that the Zn surface lateral diffu sion can extend greater than or equal to 50 mu m for samples annealed at 500 degrees C or higher temperatures. Close attention should be pai d to this anomalous lateral surface diffusion during fabrication of de vices using Zn-contained ohmic contacts.