BCN Films Research Articles

Thin-film (Al)BCN materials synthesized by sequential precursor pulses to mimic atomic layer deposition

This work brings novel insights into the existing knowledge on the deposition of films containing boron (B), carbon (C), nitrogen (N), and aluminum (Al). The (Al)BCN films are obtained at low substrate temperatures (TS) of 250–400 °C from triethylborane, ammonia (NH3), and trimethylaluminum. For BCN films, a nearly similar elemental composition of B0.42C0.41N0.15O0.02, with 1–2 at. % variations, is observed for substantial ranges of TS and NH3-exposure time. This can indicate a similar growth mechanism and/or formation of a single-phase material. While excluding precursor underdosing, a remarkable dependence of growth rate per cycle (GPC) on total gas pressure (Ptot) is observed. The GPC approaches near saturation regime for Ptot between 1 and 10 mbar, for TS = 330–375 °C, which might support the occurrence of a surface-adduct assisted pathway. The level of GPC saturation is influenced by TS. For a wide range of process conditions, N-share in the films slightly varies between 12 and 16 at. %. C-share only changes between 40 and 42 at. %. The attempt to increase N-share by dissociating NH3 into NH2 radicals by hot wire assistance remarkably shows the opposite effect, i.e., a decrease in the N-share from 15 to 6 at. %. This is accompanied by a corresponding increase in the B- and, in particular, C-shares, suggesting that the removal of carbon can occur via the incorporation of nitrogen. For AlBCN films, changing Ptot has a strong effect on their elemental composition. At Ptot = 10 mbar, Al-deficient films grow, whereas a Ptot of 0.2 mbar leads to mainly AlN-containing films with some inclusions of BN.

Tuning boron-carbon-nitride films

Materials Science Thin films formed from boron, carbon, and nitrogen (BCN films) can exhibit a wide range of optical and electronic properties if they can be made as phase-pure materials. Giusto et al. report on a simple solution-based route to hydrogenated BCN films. Gels formed with different melamine and boric acid ratios (1:1 and 2:1) were deposited on substrates and then heated in dry nitrogen to produce homogeneous, optically transparent films with optical bandgaps of 2.9 and 3.4 electron volts, respectively. The material derived from the 2:1 gel exhibited sp2 bonding and avoided segregation into graphene and hexagonal boron nitride. Addition of small amounts of benzoguanamine to the gels allowed for additional compositional and bandgap tuning. J. Am. Chem. Soc. 142 , 20883 (2020).

Modulation of ferromagnetism and transport in BxCyNz thin films via nitrogen doping and defects

Boron carbonitride (BxCyNz) represents an interesting family of materials containing all light elements and two dimensional graphene like hybrid layers. Although rich literature exists on this peculiar material in chemically processed form, there are relatively fewer reports on device application-worthy thin film form. This form also offers a natural platform for basic studies on important aspects such as magnetism and transport, which have attracted attention in the context of ferromagnetism in doped and defect carbon systems. Thus, in this work we have grown thin films of this compound using Pulsed Laser Deposition (PLD) method, and investigated their magnetic and transport properties in their entirety along with the detailed electronic structure using various spectroscopic techniques like X-ray photoelectron spectroscopy (XPS), Valence Band Spectroscopy (VBS) and X-ray absorption near edge spectroscopy (XANES). In depth analysis of the typical role of dopants and defects, especially the prevalent nitrogen defects, is elucidated using Density Functional Theory (DFT) calculations to understand the experimental observations. A dramatic crossover in the transport mechanism of charge carriers is observed in this system with the change in doping level of specific nitrogen defects. A robust and high saturation magnetization is achieved in BCN films which is higher by almost hundred times as compared to that in similarly grown undoped carbon film. An anomalous transition and increase in coercive field is also observed at low temperature. A careful analysis brings out the intriguing role of specific nitrogen defects in defining the peculiar nature and concentration dependence of the physical properties of this system.

Collaborative enhancement of photon harvesting and charge carrier dynamics in carbon nitride photoelectrode

Target-oriented photoelectrochemical (PEC) performance can be enabled by regulating the physicochemical properties of graphitic carbon nitride (CN)-based photoanodes in the PEC process. Herein, we introduced boron heteroatoms into CN films (BCN) and explored the influence of the B heteroatom on the PEC performance experimentally and theoretically. B atoms favor substitution of carbon atoms at bay sites in BCN films and reduce the bandgap by raising the valence band edge as well as constructing optimal electronic structures for PEC hydrogen production. The as-prepared BCN films exhibit nearly 4 times higher photocurrent density than that of pristine CN films. We demonstrate that such enhancement originates from the spatially complementary orbital distribution over the BCN films, thus expediting the charge carrier separation. This work proposes ideal empirical routines for multiple functionalization of CN films for diverse PEC activities via component tailored strategies.

Synthesis and characterisation of thin films in the B–C–N triangle

In this study, about 400 nm thick BCN films with different compositions were grown by reactive DC magnetron sputtering of a B4C target by varying the N2/Ar proportion in the sputtering gas from 0 to 50%. The microstructures of the films were determined by FE-SEM. The chemical composition was determined by electron probe microanalyser (EPMA). The crystallinity of the films was studied by grazing incidence XRD analyses. FTIR was used to determine the chemical bonding structures. The elemental depth profiles of the films were obtained from SIMS measurements. Nanoindentation and wear tests were used to determine the mechanical and tribological properties. Hardness, elastic modulus and wear rates of BCN films were significantly decreased with the increase of nitrogen in the coating composition. The results demonstrated that thin films in the ternary triangle B–C–N with tailored properties can easily be deposited by reactive DC magnetron sputtering with varying N2 flow rates.

Air annealing effect on scratch behaviour of BCN films

Boron carbon nitride BCN films have been deposited by direct current unbalanced magnetron sputtering. The obtained amorphous films are annealed in air atmosphere with different temperatures from 200 to 800C. The composition, microstructure, mechanical properties and scratch behaviour of BCN films were studied. The microstructures do not change significantly and mechanical properties decrease slightly when the annealing temperatures are below 400C. The films are oxidised and mechanical properties decline rapidly when annealing temperature rises to 600C. The scratch depth decrease and the highest critical load increases after the films are treated by air annealing below the oxidation temperature. The dominant deformation changes from elastic deformation to plastic deformation with the increase in annealing temperature. The coefficient of friction rise and surface smoothness decreases after BCN films are oxidised. BCN amorphous films have good interfacial adhesion before and after oxidation.

Preparation and Characterization of Boron Carbon Nitride Films on High Speed Steel Surface

In this paper, we deposited BCN films on high speed steel (HSS) substrate by magnetron sputtering. The structure and composition of the films were analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The tribological properties of the films was studied by ball-on-disc tribological test. Results show that BCN films have a certain antifriction effect, which is influenced by RF target power and substrate bias.

Mechanical properties and thermal stability of SiBCN films prepared by ion beam assisted sputter deposition

The high hardness, exceptional high temperature stability, and oxidation resistance of bulk Si–B–C–N ceramics have led to the expectation that these materials will be good candidates for superior coating materials in high-temperature applications. In this study, SiBCN films were prepared using ion beam assisted sputter (IBAS) deposition, and the mechanical properties and thermal stabilities of the films at 600, 700, and 800°C in air were investigated. In particular, the effects of the ion beam assist on the properties of the SiBCN films were examined. The SiBCN films were deposited on Si plates by sputtering a target composed of Si+BN+C using a 2-keV Ar+ ion beam. A low-energy N2+ and Ar+ mixed ion beam irradiated the samples during the sputter deposition. The Si content in the SiBCN films was controlled by changing the Si/(BN+C) ratio of the target. BCN films were also deposited for comparison. The composition and chemical bonding structure of the prepared films were investigated by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. We found that c-BN bonds were formed in the ion-assisted BCN film. The oxide layer thickness on the SiBCN films after thermal annealing decreased due to the IBAS deposition and an increase in the Si content. Ion-assisted SiBCN films annealed at 800°C showed the highest hardness of 20GPa.

Hexagonal Nano-Crystalline BCN Films Grown on Si (100) Substrate Studied by X-Ray Absorption Spectroscopy

Hexagonal nano-crystalline boron carbonitride (h-BCN) films grown on Si (100) substrate have been precisely investigated. The films were synthesized by radio frequency plasma enhanced chemical vapor deposition using tris-dimethylamino borane as a single-source molecular precursor. The deposition was performed by setting RF power at 400 - 800 W. The reaction pressure was at 2.6 Pa and the substrate temperature was recorded at 700°C - 800°C. Formation of the nano-crystalline h-BCN compound has been confirmed by X-ray diffraction analysis. The diffraction peaks at 26.3° together with a small unknown peak at 29.2° were elucidated due to the formation of an h-BCN structure. The films composed of B, C, and N atoms with different B-N, B-C, C-N chemical bonds in forming the sp2-BCN atomic configuration studied by X-ray photoelectron spectroscopy. Orientation and local structures of the h-BCN hybrid were studied by near-edge X-ray absorption fine structure (NEXAFS) measurements. The dominant presence of p* and s* resonance peaks of the sp2-hybrid orbitals in the B K-edge NEXAFS spectra revealed the formation of the sp2-BCN configuration around B atoms like-BN3 in h-BN. The orientation was suggested on the basis of the polarization dependence of B K-edge and N K-edge of the NEXAFS spectra.

701 パルス化直流プラズマCVD法によるBCN成膜(OS8-1 表面の機能化と薄膜・トライポロジー(1),OS8 表面の機能化と薄膜・トライポロジー)

701 パルス化直流プラズマCVD法によるBCN成膜(OS8-1 表面の機能化と薄膜・トライポロジー(1),OS8 表面の機能化と薄膜・トライポロジー)

Mechanical properties and bonding structure of boron carbon nitride films synthesized by dual ion beam sputtering

The BCN films were synthesized on Si (110) wafers by using dual ion beam sputtering deposition from boron carbide target. The influences of ion assist source energy and N2 relative flow rate on the surface roughness, mechanical properties and chemical bonding structure of BCN films were investigated systematically. The surface roughness was measured using non-contact optical surface profilometer and the mechanical properties of BCN films were evaluated with nano-indenter. The BCN films were characterized by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), respectively. The results showed that the BCN films' surface roughness varied in the range of 5–15 nm, and their hardness and reduced elastic modulus fluctuated in the scope of 18–29 GPa and 192–229 GPa, respectively. When the BCN films' surface roughness varied in the range of 8–12 nm, the values of hardness and reduced elastic modulus were fluctuated slightly. The BCN films with the smoothest surface (Ra = 5 nm) and the highest hardness of 28 GPa were obtained at the ion assist source energy of 200 eV and the N2 relative flow rate of 50%. The BCN films were amorphous and contained several bonding states such as B–N, B–C and C–N with B–C–N hybridization.

High Piezoelectric Properties of KNN‐Based Thick Films with Abnormal Grain Growth

Over 10 μm‐thick (K,Na)NbO3 KNN‐based films doped with complex‐perovskite‐materials (CPs) were deposited on platinized sapphire substrates by aerosol deposition (AD). Three CPs were selected: Ba(Cu1/3Nb2/3)O3 (BCN), Cu(Cu1/3Nb2/3)O3 (CCN), and Sr(Cu1/3Nb2/3)O3 (SCN). The films of 0.985(Na0.5K0.5)NbO3‐0.015CPs (KNN‐CPs) were post annealed at 1050°C for 1 h in air without any serious phase decomposition. The microstructure showed abnormal grain growth due to Cu‐rich liquid phase. The KNN–BCN film had the largest abnormal grain size of over 10 μm, whereas the KNN–SCN film had the smallest grain size and also the smallest frequency of abnormal grains. All the films exhibited typical characteristics of ferroelectric hysteresis similar to those of the bulk materials without any leakage. The KNN–BCN films possessing the biggest abnormal grains also exhibited the highest density, piezoelectric constant, and piezoelectric voltage constant of 110 pC/N and 15.45 × 10−3 Vm/N, respectively, which are the highest values reported so far for KNN‐based films. This indicated that KNN‐CPs lead‐free films are suitable candidates for sensor applications.

Reactive expansion of laser-induced boron/carbon plasma in ECR nitrogen plasma during the deposition of BCN films

The expansion of the boron/carbon plasma induced by pulsed laser ablation of B 4C in the nitrogen plasma generated by electron cyclotron resonance (ECR) microwave discharge of N 2 gas was studied by optical emission spectroscopy (OES). OES measurements show that at the initial stages the mono-atomic species ablated from B 4C are the dominant emitting species and after 0.5 μs the plasma emission evolves to be dominated by the emission bands from nitrogen molecules and nitrogen molecular ions, revealing that the N 2 gas is highly excited by the hybrid processes of ECR microwave discharge and pulsed laser ablation. In addition to the emissions emitted from the species ablated from the target and present in the reactive background, C 2 and CN emissions are also observed. The characteristics of the emissions from various species provide an access to the reactive expansion of the boron/carbon plasma in the nitrogen plasma and the gas-phase reactions occurring in the plasmas during the deposition of BCN films by nitrogen plasma assisted pulsed laser deposition. The mechanisms for efficient incorporation of nitrogen in the films were also discussed.

Effect of Target Power on Nano-Scratch Behavior of BCN Films by d.c. Reactive Magnetron Sputtering

Effect of Target Power on Nano-Scratch Behavior of BCN Films by d.c. Reactive Magnetron Sputtering

Composited BCN/carbon fibers prepared by hot-filament chemical vapor deposition

The combined BCN/carbon fibers with porous configuration have been successfully prepared by hot-filament chemical vapor deposition (HF-CVD). The composited materials consist of carbon fiber inside covered by the cylindrical BCN films. The differences in the surface morphology and the diameter of the composite fibers are related to the different reactant gases. It is demonstrated that the elements of B, C, and N are chemically bonded with atomic-level BCN hybrid in the composite fibers. The resistance of the composite fibers is about 300 Ω which is 10 times higher than that of the isolated carbon fibers (27.5 Ω). When the applying voltage increases up to 8–15 V, the BCN films have been broken down and the resistance of composite fibers decreases to the typical value of the carbon fibers. The composite fibers with porous configuration have the strongly capacity to adsorb oxygen. The findings suggest that the combined BCN/carbon fibers are favorable for achieving high performance nano-optoelectronic and sensor devices.

Elaboration and quantitative investigation of BCN‐type films by dynamic SIMS using the MCsx+ mode

AbstractA quantitative SIMS approach using MCs+ mode has been tested on boron carbonitride type films (BCN). Thick amorphous BxCyNz films of different stoichiometries (0.46 ≤ x ≤ 0.68; 0.07 ≤ y ≤ 0.43; 0.01 ≤ z ≤ 0.26), deposited by thermal chemical vapour deposition, were used as standard samples to establish calibration curves between secondary ion intensities derived from in‐depth secondary ion mass spectroscopy analyses and compositions determined by X‐ray photoelectron spectroscopy. The matrix intensity ratios I(CCs+)/I(BCs+) and I(CCs2+)/I(BCs2+) appear linear with the concentration ratios CC:CB; ratios of I(NCs+)/I(BCs+) and I(NCs2+)/I(BCs2+) appear linear with the concentration ratio CN:CB as well. These calibration curves allow the quantification of matrix species in BCN films, in the range of studied stoichiometries and can be employed for compositional determination of unknown BCN films. Copyright © 2010 John Wiley & Sons, Ltd.

Influence of the methyl group on the dielectric constant of boron carbon nitride films containing it

LSI interconnect insulators made using low dielectric constant (low-k) materials are required for high performance devices with a small RC delay. We investigated a boron carbon nitride film containing the methyl group (Me–BCN) using tris-di-methyl-amino-boron (TMAB: B[N(CH 3) 2] 3) gas as a low-k material. In addition, we studied the influence of the methyl group on the dielectric constant (k-value) and the properties of the Me–BCN films. It was found that the k-value of the Me–BCN films decreases with increasing number of C–H bonds due to the methyl group (CH 3). The number of O–H bonds due to water incorporation is suppressed by increasing the number of C–H bonds. Consequently, we suggested that a lower k-value can be realized by the suppression of water invasion by a hydrophobic surface due to methyl bonds. Thus, the control of the methyl group is important to achieve a low-k material using Me–BCN films.

Growth and characterization of stoichiometric BCN films on highly oriented pyrolytic graphite by radiofrequency plasma enhanced chemical vapor deposition

Hexagonal boron carbonitride (h-BCN) hybrid films have been synthesized on highly oriented pyrolytic graphite by radiofrequency plasma enhanced chemical vapor deposition using tris-(dimethylamino)borane as a single-source molecular precursor. The films were characterized by X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS) and Raman spectroscopic measurements. XPS measurement showed that the B atoms were bonded to C and N atoms to form the sp 2–B–C–N atomic hybrid chemical environment. The atomic composition estimated from the XPS of the typical sample was found to be almost B 1C 1N 1. NEXAFS spectra of the B K-edge and the N K-edge had the peaks due to the π* and σ* resonances of sp 2 hybrid orbitals implying the existence of the sp 2 hybrid configurations of h-BCN around the B atoms. The G band at 1592 and D band at 1352 cm − 1 in the Raman spectra also suggested the presence of the graphite-like sp 2–B–C–N atomic hybrid bonds. The films consisted of micrometer scale crystalline structure of around 10 µm thick has been confirmed by the field emission scanning electron microscopy.

Effects of nitrogen gas ratio on composition and microstructure of BCN films prepared by RF magnetron sputtering

BCN films are prepared by a radio frequency (RF) magnetron sputtering in a mixture of Ar and N 2 gases using a combination of half-moon shaped B 4C (BC) and graphite (G) targets where the substrates are faced to each target side (BC-side and G-side) which allows us to obtain the BCN films with a different composition at the same time. The compositional and structural changes are examined under the different conditions of the ratio of N 2 to Ar gases and the sample-set-positions by field emission-scanning electron microscopy/energy dispersive X-ray spectroscopy (FE-SEM/EDX), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), visible– and ultraviolet (UV)–Raman measurements. Nanoindentation test is also carried out to evaluate the mechanical properties. It is found that all films exhibit amorphous structure. With increasing N 2 ratio, the B concentration in the films is decreased, while the amount of C–N bonds is increased. For the G-side films, C concentration and the amount of B–C bonds are increased as compared with the BC-side films. The results suggest that the increase of N 2 ratio causes the decrease of sputtered B and the enhancement of C–N bond formation. In the case of the G-side films, BC 1.4N 0.4 films are obtained at N 2 ratio of 100%. The relation between the results of Raman spectroscopy and hardness of the films and possible scheme of the microstructure are discussed.

Atomic arrangement, composition and orientation of hexagonal BCN films synthesized by radiofrequency plasma enhanced CVD

Oriented hexagonal BCN films were synthesized on Si (1 0 0) substrate by radiofrequency plasma enhanced chemical vapor deposition using tris-(dimethylamino)borane as a precursor. The formation of the crystalline hexagonal BCN hybrids was confirmed by FT-IR and XRD. CH4 + H2 carrier gas increased the C content in the films in comparison with N2 carrier gas. XPS measurement showed that the films were composed of a variety of B-N, B-C, C-N bonds to form the BCN atomic hybrids. The π* resonance peak in the B K-edge NEXAFS spectra also indicated the presence of the sp2 hybrid configuration of B-C-N bonds like BN3 in h-BN. The σ* resonance peaks suggested the diversity in the σ bonds in the films. Orientation of the h-BCN hybrids was suggested on the basis of the polarization dependence of NEXAFS.