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

Abstract

Pure hexagonal h, as well as mixed-phase cubic/hexagonal c/h boron nitride ͑BN͒ thin films were deposited onto ͓001͔ silicon substrates using the dual ion beam deposition technique. The BN thin films were grown under UHV conditions at different substrate temperatures and ion beam bombarding parameters. Thin-film growth was monitored using in situ spectroscopic ellipsometry at 44 wavelengths between 420 and 761 nm. The in situ ellipsometric ⌿ and ⌬ 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 silicon substrate. The growth and nucleation of c-BN observed here confirms the cylindrical thermal spike model. The results for composition and thickness of the BN films were compared to those obtained from ex situ infrared transmission measurements and high-resolution transmission electron microscopy investigations.

The formation of epitaxial hexagonal boron nitride on nickel substrates

“…5,6 Unfortunately, much like diamond films, the synthesis of crystalline BN films is still in its early stages of development. Furthermore, although polycrystalline BN films have been prepared by a variety of physical and chemical vapor deposition techniques, 7,8,9,10,11,12,13 the capability does not currently exist for depositing large area single-crystal or oriented films of BN. Such single-crystal films are required for many of the applications of interest.…”

Analysis of defects on BN nano-structures using high-resolution electron microscopy and density-functional calculations

“…[5,6] contain comparative reviews for these models. Most discussed models include the compressive stress model [7][8][9], preferential sputtering model [10,11], sub-plantation model [12][13][14][15], thermal spike model [16][17][18], and the nanoarches model [5]. It has been observed that, after the cubic phase nucleates on top of the h-BN basal planes, the energy of the ions could be lowered significantly while the growth of the cubic phase is maintained [19].…”

Ultraviolet-extended real-time spectroscopic ellipsometry for characterization of phase evolution in BN thin films

“…RTSE in the visible range ͑1.6-3.0 eV͒ has been applied recently to study BN film growth. 5 The poor optical contrast between hBN and cBN in this range, however, makes it difficult to distinguish the phase evolution from possible microstructural evolution ͑e.g., void fraction variations͒. Bulk cBN is isotropic with an index of refraction in the visible spectral range of nϳ2.1; hBN is uniaxial with values of the ordinary and extraordinary indices of n o ϳ2.17 and n e ϳ1.65, respectively.…”