In situ ellipsometry growth characterization of dual ion beam deposited boron nitride thin films

Pure hexagonal h, as well as mixed-phase cubic/hexagonal c/h boron nitride (BN) thin films were deposited onto [001] silicon substrates using the dual ion beam deposition technique. The BN thin films were grown under UHV cond itions at different substrate temperatures and ion beam bombarding paramete rs. Thin-film growth was monitored using in situ spectroscopic ellipsometry at 44 wavelengths between 420 and 761 nm. The in situ ellipsometric Psi an d Delta data were compared with two-layer growth model calculations for the mixed-phase c/h BN, and with one-layer growth model calculations for pure h-BN growth. In situ data provide information on the optical properties of deposited h-BN and c/h-BN material, film thickness, and BN growth rates. A virtual interface approach is employed for the optical properties of the si licon substrate. The growth and nucleation of c-BN observed here confirms t he cylindrical thermal spike model. The results for composition and thickne ss of the BN films were compared to those obtained from ex situ infrared tr ansmission measurements and high-resolution transmission electron microscop y investigations. (C) 2000 American Institute of Physics. [S0021-8979(00)08 705-3].