Electronic state and glow discharge decomposition of tetramethyldisilane

Tetramethyldisilane, a new source gas for amorphous silicon carbide, was decomposed by an rf glow discharge. Its reactivity in the formation of amorphous films was higher than a mixture of monosilane and methane gases. A plasma diagnosis by optical emission spectroscopy was contrastive between the two source gas systems, being consistent with the bond energy of the gases determined by a semi-empirical molecular orbital calculation. Judging from the rf power and the substrate temperature dependences on the optical band gaps of the films, the films prepared from tetramethyldisilane have optical band gaps wider than 2.2 eV and their structures appear to be different from those prepared from a monosilane/methane (1/2) gas mixture under otherwise the same conditions. Carbon and silicon atoms are apparently distributed more homogeneously in the former films than in the latter films.