Investigation of thin film growth of B12As2 by chemical vapor deposition

The chemical vapor deposition of icosahedral boron arsenide, B12As2, on 6H-SiC (0001) (on and off-axis) substrates was studied using hydrides as the reactants. The effects of temperature and reactant flow rates on the phases deposited and the crystal quality were determined. The growth rate increased with temperature from 1.5mum/h at 1100 degreesC to 5 mum/h at 1400 degreesC and decreased thereafter. X-ray diffraction revealed that the deposits were amorphous when the deposition temperature is below 1150 degreesC. Above 1150 degreesC, smooth B12As2 films were formed on 6H-SiC substrates with an orientation of (0001) B12As2 parallel to 6H-SiC (0001). Raman spectroscopy confirmed the strongly c-axis oriented nature of B12As2 film on 6H-SiC.