Chemical Vapor Deposition of Sp2-Boron Nitride on Si(111) Substrates from Triethylboron and Ammonia: Effect of Surface Treatments

Thin films of the sp²-hybridized polytypes of boron nitride are interesting materials for several electronic applications such as UV-devices. Deposition of epitaxial sp²-BN films has been demonstrated on several technologically important semiconductor substrates such as SiC and Al₂O₃ and where controlled thin film growth on Si would be beneficial for integration of sp²-BN in many electronic device systems. We investigate growth of BN films on Si(111) by chemical vapor deposition from triethylboron B(C₂H₅)₃ and ammonia NH₃ at 1300 °C with focus on treatments of the Si(111) surface by nitridation, carbidization and nitridation followed by carbidization prior to BN growth. Fourier transform infrared spectroscopy shows that the BN films deposited exhibit sp² bonding. X-ray diffraction reveals that the sp²-BN films predominantly grow amorphous on untreated and pre-treated Si(111), but with diffraction data showing that turbostratic BN can be deposited on Si(111) when the formation of Si₃N₄ is avoided. We accomplish this condition by a nitridation procedure in a deposition chamber where B_xC had previously been deposited at high temperature, but where the synthesis route needs to be further developed for a better process control.