STRATEGIES FOR THE SYNTHESIS OF HIGHLY CONCENTRATED SI1-YCY DIAMOND-STRUCTURED SYSTEMS

Precursor chemistry and ultrahigh-vacuum chemical vapor deposition hav e been used to deposit Si1-yCy thin films on (001) Si substrates. Film s with carbon compositions ranging up to 20 at. % were deposited at su bstrate temperatures of 600-740 degrees C using gas mixtures of SiH4 w ith C(SiH3)(4) or C(SiH2Cl)(4), which an (C-H)-free precursors incorpo rating Si4C tetrahedra. The composition of the resulting materials was obtained by Rutherford backscattering spectrometry, including carbon resonance analysis. Cross-sectional transmission electron microscopy a nd infrared spectroscopy were used to provide microstructural and bond ing information. Raman spectroscopy suggested that the substitutional C concentration obtained using this protocol was higher than that obta ined by other methods. The addition of small amounts of GeH4 to the ga s mixture had a remarkable effect on growth rates and film crystallini ty. (C) 1998 American Institute of Physics.