Lattice site location studies of ion implanted 8Li in GaN

The lattice sites of ion implanted Li atoms in GaN were studied as a function of implantation temperature between room temperature and 770 K. We measured the channeling and blocking patterns of alpha-particles emitted in the radioactive decay of implanted Li-8 ions to determine the Li lattice sites. Below 700 K Li atoms occupy mainly interstitial sites in the center of the c-axis hexagons at positions c/4 and 3c/4, where c is the lattice constant in c-axis direction. Around 700 K Li starts to diffuse and presumably interacts with vacancies created in the implantation process. This leads to the formation of substitutional Li above 700 K. An activation energy of about 1.7 eV for interstitial Li diffusion was determined. (C) 1998 American Institute of Physics.