Self-diffusion of gallium and antimony in GaSb

Abstract

Self-diffusion of gallium and antimony in GaSb has been investigated in both Ga-saturated and Sb-saturated single crystals at temperatures ranging from 867 K to the temperature of congruent melting. The radio-isotopes ⁷²Ga and ^I22 Sb were diffused simultaneously to avoid composition gradients. After sputter-sectioning, the penetration profiles for both isotopes were obtained by means of a Ge(Li) spectrometer. It is found that Ga diffuses slightly faster than Sb and that the composition plays an important role: Ga and Sb diffuse faster in Sb-rich than in Ga-rich samples. The temperature dependence of both diffusivities resembles that of the Sb partial pressure over the compound. Several mechanisms of diffusion are discussed in the light of these observations. The coupled diffusion of Ga and Sb leads us to conclude that both components diffuse via the same defect. In view of the special type of defect structure in GaSb, we propose that the triple defect is the predominant diffusion vehicle for both components.