Crystallization process of amorphous silicon-carbon alloys

The crystallization behavior of amorphous silicon carbon alloys films was investigated using infrared spectroscopy and transmission electron microscopy. The films were prepared by plasma enhanced chemical vapor deposition and the thickness and composition were checked by Rutherford backscattering spectroscopy. Annealing processes were carried out in the temperature range of 750-1100 °C in a vacuum furnace. The changes in the infrared absorption band (400-1200 cm-1) after annealing indicate a transition from amorphous to a crystalline phase. The onset temperature for this transition depends on the alloy composition, and it increases from 800 to 950 °C with increasing carbon concentration. The microstructure of crystallized SiC is influenced by the film composition. Transmission electron microscopy (TEM) analysis shows that the crystallized stoichiometric alloy is composed by polycrystalline b-SiC grains. TEM and Raman spectroscopy evidenced that in silicon rich and carbon rich alloys, the beta-SiC grains are surrounded by silicon grains and graphitic clusters, respectively.