Influence of Carbon Content on the Crystallographic Structure of Boron Carbide Films

Heteroepitaxial boron carbide (BxC) can be grown on Si face 4H-SiC(0001) using a two-step process involving substrate boridation at 1200$^\circ$C under BCl3 + H2 followed by a chemical vapor deposition (CVD) growth step at 1600$^\circ$C by adding C3H8 precursor. However, in-depth investigation of the early growth stages revealed that complex reactions occur before starting the CVD at high temperature. Indeed, after boridation, the 35 nm BxC buffer layer is covered by an amorp...

The crystal structure and chemical bonding of magnetron-sputtering deposited nickel carbide Ni$_{1-x}$C$_{x}$ (0.05$\leq$x$\leq$0.62) thin films have been investigated by high-resolution X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and soft X-ray absorption spectroscopy. By using X-ray as well as electron diffraction, we found carbon-containing hcp-Ni (hcp-NiC$_{y}$ phase), instead of the expected rhombohedral-Ni$_...

In this work, the successful heteroepitaxial growth of boron carbide (B x C) on 4HSiC(0001) 4{\textdegree} off substrate using chemical vapor deposition (CVD) is reported. Towards this end, a two-step procedure was developed, involving the 4H-SiC substrate boridation under BCl 3 precursor at 1200{\textdegree}C, followed by conventional CVD under BCl 3 + C 3 H 8 at 1600{\textdegree}C. Such a procedure allowed obtaining reproducibly monocrystalline (0001) oriented films of B x ...

Ultrananocrystalline diamond/hydrogenated amorphous carbon composite thin films synthesized via coaxial arc plasma possess a marked structural feature of diamond grains embedded in an amorphous carbon and a hydrogenated amorphous carbon matrix which are the largest constituents of the films. Since the amorphous nature yields much larger light absorption coefficients as well as a generation source of photo-induced carriers with UV rays, these films can be potential candidates ...

We study how the substrate temperature influences the structural properties of carbon films deposited by PVD (physical vapor deposition) techniques. We adapted a heating system inside the deposition chamber, with temperatures up to 700$^{\circ}$C. Here we develop an experimental setup that allows us to obtain large films of the desired material on any substrate, with deposition times of the order of a minute. The characterization is based mainly on the analysis of the Raman s...

Hexagonal boron nitride (hBN) regains interest as a strategic component in graphene engineering and in van der Waals heterostructures built with two dimensional materials. It is crucial then, to handle reliable characterization techniques capable to assess the quality of structural and electronic properties of the hBN material used. We present here characterization procedures based on optical spectroscopies, namely cathodoluminescence and Raman, with the additional support of...

The structural modifications of polycrystalline hexagonal boron nitride implanted with He+ ion beams at energies between 200 keV and 1.2 MeV to fluences of 1.0 \times 1017 ions \cdot cm-2 were investigated using micro-Raman spectroscopy. The measured Raman spectra show evidence of implantation-induced structural transformations from the hexagonal phase to nanocrystalline cubic boron nitride, rhombohedral boron nitride and amorphous boron nitride phases. The first-order Longit...

We present a first-principles computational study of the thermodynamics of carbon defects in hexagonal boron nitride (hBN). The defects considered are carbon monomers, dimers, trimers, and larger carbon clusters, as well as complexes of carbon with vacancies, antisites, and substitutional oxygen. Our calculations show that monomers ($\text{C}_{\text{B}}$, $\text{C}_{\text{B}}$), dimers, trimers, and $\text{C}_{\text{N}}\text{O}_{\text{N}}$ pairs are the most prevalent species...

Hexagonal boron nitride (h-BN) is a critical material for 2D electronic devices for graphene and has attracted a considerable amount of attention owing to its structural similarity and semiconducting property. However, modifying its wide-band gap is a challenge. Hydrogenation is a potential method of altering the electrical properties, although is seldom experimentally measured. Here, the complex permittivity of h-BN after various hydrogen treatments have been investigated. F...

Different peak trends of tiny grains carbon film have been observed under the investigations of Raman spectroscopy and energy loss spectroscopy. Carbon films known in nanocrystalline and ultra-nanocrystalline diamond films are synthesized by employing microwave-based vapor deposition system. Carbon atoms exhibit several state behaviors depending on the incurred positions of their electrons. Different morphology of tiny grains under different chamber pressure is related to dif...