The aim here was to compare the diffusion coefficient and the shape of the Mn atomic profile in GaAs, treated under various annealing conditions. Diffusion was performed from implanted Mn as well as from external source of Mn. Manganese-implanted GaAs, GaAs:Zn and GaAs:Te bulk samples were investigated. Implantation was performed at room temperature to a dose of 1016/cm2 at an energy of 150keV. The samples, were protected with AlN layers, and annealed at 800C with rapid thermal annealing method as well as at 700 and 900C in a sealed quartz ampoule. After removing the AlN films the extent of diffusion of the species was characterized using the secondary ion mass spectrometry technique. The depth profiles of in-diffused manganese in rapid thermal annealing experiment strongly indicated that the diffusion coefficient D was concentration-dependent. For both: quartz ampoule and rapid thermal annealing 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 was 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 indicated highest Mn diffusivity in the sample with a low Fermi level which provided lowest concentration of ionized Ga vacancies. Both results confirmed 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.

Diffusion of Mn in Gallium Arsenide. R.Jakieła, A.Barcz, E.Wegner, A.Zagojski: Journal of Alloys and Compounds, 2006, 423[1-2], 132-5