A Thermodynamic Estimation of the Chemical Vapor Deposition of Some Borides

Boron thin films were deposited by electron beam evaporation and by pyrolysis of decaborane on quartz substrates. Reflection electron beam diffraction was used to characterize the crystal structure. The amorphous structure was observed for the film deposited by electron beam evaporation. The film was polycrystalline alpha-rhombohedral boron when the film was deposited by pyrolysis. All samples showed p-type conduction. The conductance of the film deposited by electron beam evaporation decreased linearly against T4. Linear relation was observed in the log sigmaagainst T-1 plot for the film deposited by pyrolysis. The thermoelectric power of the film deposited by electron beam evaporation decreased from 500 to 300 muV/K as the temperature increased from 300 to 800 K. The power factor increased from 10-9 to 10-6 V2omega-1K-2 cm-1 with increasing temperature from 300 to 800 K.