Study of defects in Si+ implanted GaAs layers by X-ray diffraction method

SI-GaAs (001) wafers were implanted by Si⁺ ions at 50 keV and various doses (1-10¹⁵, 1-10¹⁴ and 1-10¹² cm^-2). The as-implanted samples were annealed during 10 min at 850°C in arsine air. The samples were studied by high-resolution X-ray diffraction (HRXRD) method. The strain profiles obtained from the fitting were recalculated into point defects concentration profiles taking into account an influence of Frenkel´s pairs on a lattice parameter. To build the point defects concentration profile TRIM90 program was also used. The built profile was compared to one obtained from fitting of HRXRD data. The difference between HRXRD and TRIM90 results was found to decrease with decreasing of an implantation dose. However, in any case the point defect concentration in real crystal is significantly less than one calculated by TRIM90 program. The results confirm the fact of separation of the Frenkel´s pair components and quicker sink of the interstitials to the surface. Annealing reduces concentration of Frenkel´s pairs and leads to increase of the thickness of the distorted layer