Diffusion of Mn in gallium arsenide

The depth profiles of in-diffused manganese in RTA experiment strongly indicate that the diffusion coefficient D is concentration-dependent. For both: quartz ampoule and RTA annealings of implanted samples, the Mn diffusivity was found larger when GaAs was annealed with the AlN cap than that annealed without a cap. Over 10 times shallower diffusion range in uncovered samples than those encapsulated with AlN is interpreted in terms of generation of additional vacancies in the Ga sub-lattice. Mn atoms incorporate in Ga sites lowering thus the diffusion coefficient. In case of diffusion from external source into differently doped GaAs, the largest diffusion coefficient was found for GaAs:Zn. This result indicates highest Mn diffusivity in the sample with a low Fermi level which provides lowest concentration of ionized Ga vacancies. Both results confirm an interstitial diffusion mechanism and decreasing diffusion coefficient with increasing gallium vacancy concentration. The Boltzmann-Matano analysis was employed to evaluate the concentration-dependent diffusion coefficient of Mn in GaAs.