Structural relaxation processes in amorphous material were investigated by means of Raman spectroscopy and positron lifetime measurements. Bond-angle deviations and the sizes of vacancy-type defects were estimated in ion-beam amorphized and plasma chemical vapor-deposited amorphous samples. It was found that, during annealing at 450C, the bond-angle deviation decreased appreciably, and only vacancies which were smaller than the di-vacancy were observed in the ion-amorphized samples. In the case of the plasma-deposited samples, large vacancy clusters were formed and the bond-angle deviation was essentially constant. This indicated that relaxation processes were suppressed in the latter material. The results suggested that large vacancy-type defects could stabilize amorphous structures.

T.Motooka, Y.Hiroyama, R.Suzuki, T.Ohdaira, Y.Hirano, F.Sato: Japanese Journal of Applied Physics, 1995, 34[II-2A], L149-52