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.