Lattice site and diffusion of ion-implanted Li in as-grown and Se-rich ZnSe

Abstract

The implantation sites and diffusion of Li in as-grown and Se-rich ZnSe has been studied with emission channeling measurements on the α-particles emitted in the decay of radioactive 8Li probes implanted in single-crystal samples. At implantation temperatures below 180 K the Li atoms are immobile at tetrahedral interstitial sites, but a site change sets in at 200 K, and above 250 K the Li atoms occupy mainly substitutional sites. In Se-rich ZnSe the interstitial Li fraction (fT) shows partial recovery between 260 and 360 K, a phenomenon which may be attributed to Li trapping at interstitial Se. Implantation dose, however, has a strong influence on the observed channeling and blocking patterns. Maximum fT is achieved at T⩾400 K where the fraction at interstitial sites is an order of magnitude lower. At higher temperatures (≈ 550 K) the Li atoms dissociate from their substitutional sites and diffuse to the surface in the Se-rich sample and to extended defects in the implantation region in the as-grown sample.