VIBRATIONAL ANALYSIS OF COMPOSITIONAL DISORDER IN AMORPHOUS-SILICON CARBON ALLOYS

Raman and Infrared spectroscopies have been used to characterise the c ompositional disorder in a-Si1-xCx alloys. Samples with different carb on concentration have been prepared by ion implantation of carbon into a silicon matrix and have been annealed at different temperatures in order to follow the evolution of disorder. The obtained results show a n increase of the magnitude of compositional disorder with carbon conc entration and a reduction of such a disorder upon thermal treatments u p to 1000 degrees C where it vanish during the amorphous-to-crystallin e phase transition. A quantitative interpretation of the compositional disorder has been given as a function of the carbon concentration and annealing temperature.