Li-Defect Reactions During Low Dose Ion Implantation of 8 LI into ZNSE Single Crystals

We present lattice site location and diffusion studies of ion implanted 8 Li in ZnSe single crystals at sample temperatures between 180 K and 550 K using the emission channeling technique. Below 200 K, Li is immobile in ZnSe and occupies tetrahedral interstitial sites. Above 250 K, interstitial Li becomes mobile and for an accumulated dose above 1×10 12 cm -2 the majority of the implanted Li atoms occupy substitutional sites, presumably Zn sites. However, for room temperature implantation at doses below 1×10 12 cm -2 , the majority of implanted Li still occupies interstitial sites. This behavior is explained by recombination processes between Zn interstitials and vacancies, thus reducing the vacancy concentration and maintaining a high fraction of interstitial Li. Substitutional Li is stable up to about 500 K and diffuses out for temperatures above. We calculate 0.5 eV for the migration energy of interstitial Li and 1.38 eV for the binding energy of substitutional Li.