Site changes of ion-implanted Li in GaAs below 300 K.

The lattice sites of implanted Li in GaAs single crystals have been determined between 80 and 300 K by measuring channeling and blocking effects of \ensuremath{\alpha} particles emitted in the decay of implanted radioactive $^{8}\mathrm{Li}$. Below 220 K the tetrahedral interstitial site is preferentially occupied, whereas between 220 and 300 K substitutional and irregular sites are increasingly populated. These site changes are attributed to, respectively, reactions with negatively charged Ga vacancies and defect complexes in recovery stages I and II of GaAs.