The Ci and CiCs defects which were created by the proton irradiation of n-type strain-relaxed epitaxial Si1-xGex, where x was between 0.005 and 0.5, were studied by using deep-level transient spectroscopy. The ionization enthalpies of the 2 defects relative to the conduction band edge were found to increase linearly with increasing Ge content. It was shown that the corresponding levels were not pinned to any of the band edges. It was also shown that the slopes of ionisation-enthalpy versus x plots were similar for both defects, as were the full-widths at half-maximum of the corresponding deep level transient spectroscopy peaks. The observations suggested that, for both defects, the trapped electron was preferentially located at the Ci atom; because of its larger electronegativity as compared with those of Si or Ge. The annealing temperature of the Ci defect, and the in-growth temperature of the CiCs complex, increased with increasing Ge content. This was equivalent to an increasing retardation of the diffusion of Ci with increasing Ge content.

Carbon-Related Defects in Proton-Irradiated n-Type Epitaxial SiGe T.P.Leervad Pedersen, A.Nylandsted Larsen, A.Mesli: Applied Physics Letters, 1999, 75[26], 4085-7