Diffusion of zinc into ion-implanted gallium arsenide

A study has been made of the diffusion of zinc, from a vapour source, into GaAs slices which had been previously implanted with various ion species. A radiotracer sectioning technique was used to measure the zinc diffusion profiles. It was found that the various implanted ion species (H+, He+, N+, Zn+, As+, As+) had different effects on the zinc diffusion. The results could not be attributed solely to native defects produced by radiation damage. The heavier ion species increased the zinc concentration in the implanted region, but not beyond. The lighter species substantially increased the zinc diffusion rate and altered the resultant concentration profiles. Uphill diffusion was seen in slices which had been given a single high energy H+ implant. The results obtained are compared to those of Radiation-Enhanced-Diffusion experiments. It is suggested that the rate of incorporation of dopant species into the host semiconductor lattice is an important influence on the diffusion mechanism and the shape of the concentration profile. (author)