Special features of electrical activation of 28Si in single-crystal and epitaxial GaAs subjected to rapid thermal annealing

Concentration profiles of 28Si implanted in single-crystal and epitaxial GaAs were determined by measuring the C-V characteristics after the postimplantation rapid thermal annealings for 12 s at T=825, 870, and 905°C. The temperature dependence of Hall mobility of electrons in the Si-implanted layers subjected to the same annealings was determined by the Van der Pauw method within the range of 70–400 K. As distinct from conventional thermal annealing (for 30 min at 800°C), the rapid thermal annealing brings about a diffusive redistribution of silicon to deeper layers of GaAs for the materials of both types, with the diffusivity of silicon being twice as high in single-crystal GaAs as that in GaAs epitaxial layers. Analysis of temperature dependence of electron mobility in ion-implanted layers following a rapid thermal annealing indicates a significantly lower concentration of the defects limiting the mobility as compared to the case of a conventional thermal annealing for 30 min.