Thermodynamics of Preparing BxC Condensed Phases by CVD Using BCl3-CH4-H2 as Precursors

The products of self-healing phase BxC were examined as a function of temperature and initial gas molar ratios of BCl3:(BCl3+CH4) and H2:(BCl3+CH4) by complete thermodynamic equilibrium analysis. The results show that the composition of the condensed phase is quite sensitive to temperature and the molar ratios of BCl3:(BCl3+CH4) and H2:(BCl3+CH4). Based on our calculation, the ideal conditions for BxC deposition are as follows: the ratio of BCl3:(BCl3+CH4) is 0.8, the ratio of H2:(BCl3+CH4) ranges from 10 to 105.2, and the temperature is above 950 K. We found that the carbon-richment or boron-richment in materials are mainly adjusted by the ratios of BCl3:(BCl3+CH4) and H2:(BCl3+CH4).