Lattice sites of Li in CdTe

The lattice site occupation of Li in CdTe at temperatures between 40 and 500 K was investigated with the emission channeling method. Radioactive Li-8 ions were implanted at low doses into CdTe single crystals. Emission channeling patterns of alpha-particles emitted in the nuclear decay of Li-8 (t(1/2) = 838 ms) were measured and compared to calculated emission channeling and blocking effects. At temperatures below 130 K the Li ions occupy mainly tetrahedral interstitial sites and about 10% substitutional sites. In the temperature range between 130 and 190 K, a site change from the tetrahedral interstitial sites to substitutional sites is observed. Between 190 and 470 K, in addition to the substitutional Li, all samples show Li at sites, which are displaced 0.7(1) Angstrom from the substitutional position, either along the [111] axis or [100] axis. Above 470 K out-diffusion of Li to the surface is observed.