Local structure of S impurities in gaAs

The local structure of S implanted in GaAs has been determined by extended x-ray-absorption fine structure by monitoring of the S K fluorescence yield. The S first-neighbor shell shows a significant static broadening compared to the S second- and third-neighbor shells. This indicates two S configurations of approximately equal population: (1) substitutional S on an As site and (2) a complex formed by S on an As site and an As vacancy on the second-neighbor shell with a S-first-neighbor distance relaxation of 0.14 0.04. The two-site configuration explains the disparity between implanted S concentration and net electrical activity. © 1986 The American Physical Society.