LATTICE SITE LOCATION STUDIES OF ION-IMPLANTED LI-8 IN GAN

The lattice sites of ion implanted Li atoms in GaN were studied as a f unction 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 t he Li lattice sites. Below 700 K Li atoms occupy mainly interstitial s ites in the center of the c-axis hexagons at positions c/4 and 3c/4, w here c is the lattice constant in c-axis direction. Around 700 K Li st arts to diffuse and presumably interacts with vacancies created in the implantation process. This leads to the formation of substitutional L i above 700 K. An activation energy of about 1.7 eV for interstitial L i diffusion was determined. (C) 1998 American Institute of Physics.