Lattice site location of ion-implanted Li-8 in Silicon Carbide

Abstract

The lattice sites of ion-implanted Li atoms in 6H-, 4H-, and 3C-SiC were studied. Radioactive Li-8 ions (t(1/2)=0.84 s) were implanted with 60 keV into the crystalline SiC samples, and the channeling and blocking effects of 1.6 MeV alpha particles emitted in the decay were measured to determine the Li lattice sites. The alpha emission channeling spectra measured along different crystallographic directions reveal that Li occupies mainly interstitial sites with tetrahedral symmetry, centered along the c-axis atom rows in the hexagonal lattices. In the cubic 3C-SiC structure, Li is located on tetrahedral interstitial sites as well. For 6H-SiC, the implantation temperature was varied between 200 and 823 K without observing significant changes in the emission channeling spectra. Thus, Li diffusion or Li defect interaction resulting in a lattice site change does not occur in this temperature regime. (C) 2002 American Institute of Physics.