Effect of annealing in air on the properties of carbon-rich amorphous silicon carbide films

Thermal stability of thin carbon-rich Si carbide films was studied. Air anneals at the temperatures up to 700 °C were used to model the operation thermal conditions of the films in photoelectronic devices such as solar cells covered by Si carbide antireflection coatings. Si carbide films with different carbon-to-silicon ratios were studied. Annealing in air was shown to lead to consecutive film oxidation and transformation from Si carbides to oxidized Si carbide composites. The oxidized composites demonstrated the changes in thickness, element composition and optical properties as compared to the non-annealed films. At this, the films with higher Si content showed better stability of the optical properties at increased temperatures. During annealing, the increase of the film thickness by Si oxide formation competed with the thickness decrease by formation and evaporation of carbon oxide.