Zinc and gallium diffusion in gallium antimonide

摘要

Extrinsic diffusion of zinc (Zn) in gallium antimonide (GaSb) under Ga-rich conditions was analyzed on the basis of the kick-out and the dissociative diffusion mechanism. Accurate modeling of the experimental profiles by means of continuum theoretical calculations reveals that Zn diffusion proceeds via singly positively charged Zn interstitials (Zn_i~+). The changeover of Zn_i~+ to substitutional gallium (Ga) sites, thereby forming the acceptor dopant Zn_(Ga)~-, is concluded to be mainly mediated by neutral I_(Ga)~0 and singly positively charged Ga interstitials I_(Ga)~+ via the kick-out mechanism. Fitting of the Zn profiles provides the reduced Zn_i~+-mediated Zn diffusion coefficient and the relative contributions of I_(Ga)~0 and I_(Ga)~+ to Ga diffusion. These contributions to Ga diffusion are lower than the directly measured Ga diffusion coefficient, which indicates that Ga diffusion in GaSb is rather mediated by Ga vacancies than by Ga interstitials even under Ga-rich conditions. This finding supports the transformation reaction between native point defects in GaSb that was previously proposed to explain the Ga-vacancy-mediated diffusion of Ga in GaSb under Ga-rich conditions [H. Bracht et al. Nature (London) 408, 69 (2000)].