Degradation of the doping profile of epitaxial GaAs layers due to an ion implantation process

In order to form an n+ layer on the top of n/n- epitaxial layers, Si+ was implanted into vapor epitaxial GaAs wafers. When the dopant of the epitaxial layer was sulfur, a significant doping profile degradation occurred at the interface of the n/n- epitaxial layers. A similar degradation was observed in Ar+-implanted sulfur-doped epitaxial layers. Degradation of the doping profile was quite small when silicon-doped epitaxial layers were used. These results can be explained by a radiation-enhanced diffusion of the doped sulfur in the epitaxial layer.