Amorphous films of C- and H-doped material were studied, using positron lifetime spectroscopy, with regard to the structural defects which formed as a result of adding C. The results clearly revealed that there was a change in the type of defect with increasing C content. At low concentrations, the defects were mainly of vacancy type. They were similar to those in H-doped material, but had a greater trapping cross-section that was due to the presence of a more electronegative C atom in the network. As the C concentration increased, the micro-void content sharply increased. An interesting aspect of the positron lifetime data was that they reflected the chemical effects, of the incorporation of C, upon the charge-trapping behavior of the vacancies.

R.O.Dusane, S.V.Rajarshi, D.J.Goyal, V.G.Bhide, T.Nagrajan: Journal of Applied Physics, 1994, 76[1], 242-5