TRAPPING, DIFFUSION AND RELEASE OF HELIUM IN SINGLE-CRYSTAL TIC OBSERVED BY THERMAL-DESORPTION SPECTROMETRY

Using thermal desorption spectrometry (TDS), the interaction of ion-implanted helium atoms and atomic-scale defects in titanium carbide was investigated. It is found that trapping and release of helium in off-stoichiometric single-crystal TiC0.924 can be well described by a diffusive, single activation energy (2.5 eV) process. This energy is attributed to the release of a helium atom from a carbon vacancy. The experimental spectra are in excellent agreement with results obtained from diffusion theory in the presence of sinks and sources; at low implantation energies the projected range of helium is larger than the theoretical predictions and the range straggling is found to be 67 +/- 3 angstrom, independent of the implantation energy (0.1-3 keV).