Amorphous Carbon Nitride Thin Films Research Articles

Deposition of amorphous carbon nitride thin films using pressure-gradient RF magnetron sputtering and their chemical bonding structures

Amorphous carbon nitride (a-CNx) thin films were deposited through radio frequency (RF) magnetron sputtering under increasing nitrogen gas pressure around a graphite target to provide nitrogen radicals at high concentrations. The basic properties of the films, mainly chemical bonding structures, were evaluated using X-ray photoelectron spectroscopy (XPS), soft X-ray emission spectroscopy (SXES), and near-edge X-ray absorption fine structure (NEXAFS), and compared with other films deposited through the common sputtering mode, i.e., at a uniform gas pressure in the chamber. To increase the gas pressure around the graphite target, the deposition rate was slightly increased, and the chemical bonding structure of the a-CNx films was changed. However, the nitrogen content in the a-CNx films obtained from XPS analysis did not increase when the nitrogen gas pressure around the graphite target was increased. The effect of nitrogen incorporation on the a-CNx films was comparatively more effective at higher RF powers. The intensity ratio of sp3-σ and sp2-σ in the SXES spectra of the films increased with increasing RF power, from 85 W to 130 W, then decreased with a further increase in the RF power. This trend was confirmed by the peaks in the C K-edge of the NEXAFS spectra.

(Invited) Comparison of Compositional, Optical and Mechanical Properties of Sicn Thin Films Prepared By Ecr-PECVD with Different Hydrocarbon Precursors

Silicon carbon nitride (SiCN) ternary compounds present remarkable mechanical strength, bandgap tunability, optical responsivity in the UV region, and dielectric performance in microelectronics due to the combined features of silicon nitride (SiN), silicon carbide (SiC), and carbonitride (CN) [1]. The SiCN compounds can be formed using fabrication methods such as physical vapor deposition (PVD), chemical vapor deposition (CVD), and chemical synthesis. Successful SiCN thin films fabricated with different techniques and their characteristics have been reported extensively in the literature; however, the influence of hydrocarbon gas precursors has not drawn the same amount of attention for SiCN. Chemical, physical, and mechanical properties of thin films are determined by the growth parameters and the choice of sources used, like the organic single-molecule (methylsilazanes) or highly pure individual gas precursors [2,3]. The chemical vapor deposition systems mainly affect the energy of bombarding ions. Plasma-enhanced CVD has been commonly used for thin-film depositions since it provides low deposition temperature, high purity, good step coverage, and easy control of reaction parameters.Our work focuses on the electron-cyclotron resonance plasma-enhanced chemical vapor deposition (ECR PECVD) method to fabricate SiCN thin films. This method differs from other PECVD methods because it can generate a dense, highly ionized plasma (1011 ions/cm3) and ion impingement energies on the substrate as low as 20 eV [4]. A combination of argon diluted silane (SiH4) and molecular nitrogen (N2) are utilized. For carbon incorporation, we explored the influence of methane (CH4), acetylene (C2H2), and ethane (C2H6) hydrocarbon gas precursors on SiCN thin film properties. The stoichiometry, density of the thin film, optical constants, and the bonding structure of SiCN thin films as a function of hydrocarbon carbon flow rates are presented. Due to the hydrogen-containing precursors used, the silicon carbonitride films deposited by CVD methods contain a significant amount of hydrogen (H), lowest for C2H2 and highest for C2H6. Nearly stoichiometric silicon nitride and silicon carbide thin films were also prepared to interpret the measurements further. From Rutherford backscattering spectrometry (RBS) and elastic recoil detection (ERD) analysis, quantitative elemental composition distributions including H were found for films deposited with both carbon sources. For further investigation of the bonding structure of SiCN, Fourier Transform Infrared (FTIR) Spectroscopy was performed. Furthermore, we studied the hardness and Young’s modulus by nanoindentation, and optical constants were measured by variable angle spectroscopic ellipsometry (VASE).[1] C.W. Chen, C.C. Huang, Y.Y. Lin, L.C. Chen, K.H. Chen, W.F. Su, Optical prop- erties and photoconductivity of amorphous silicon carbon nitride thin film and its application for UV detection, Diamond Relat. Mater. 14 (3-7) (2005) 1010–1013.[2] Schwarz-Selinger, T., Von Keudell, A., & Jacob, W. (1999). Plasma chemical vapor deposition of hydrocarbon films: The influence of hydrocarbon source gas on the film properties. Journal of Applied Physics, 86(7), 3988-3996.[3] V.I. Ivashchenko, A.O. Kozak, O.K. Porada, L.A. Ivashchenko, O.K. Sinelnichenko, O.S. Lytvyn, T.V. Tomila, V.J. Malakhov, Characterization of SiCN thin films: experimental and theoretical investigations, Thin Solid Films 569 (2014) 57–63.[4] M. G. Boudreau, "SiOxNy Waveguides Deposited by ECR-PECVD", M.Eng. thesis, McMaster University, 1993.

Visible light irradiation effects on chemical bonding structure of amorphous carbon nitride thin films using synchrotron radiation infrared rays

Using high-intensity infrared (IR) rays from the SPring-8 synchrotron radiation, we investigated the relationship between the photo-induced deformation and the in-plane distribution of the chemical bonding state of amorphous carbon nitride (a-CNx) thin films prepared via reactive sputtering. The film deposited at 573 K has the largest amount of photo-induced deformation and the film deposited at 873 K shows no photoresponse. When the beam diameter was reduced to a few micrometers, the films were irradiated with IR rays to obtain the IR spectra at each point on the film surface. Consequently, it was discovered that the chemical bonding state of the a-CNx thin films was not uniform in the plane, and that the spectral intensity in the range of 1100–1800 cm−1 was stronger or weaker depending on the location. When irradiated with a visible light laser, the absorption band spectral intensity was assigned based on a sixfold ring structure containing nitrogen and the CN chain increased by 8%–10% in a film that underwent photo-induced deformation. In the a-CNx film with no photo-induced deformation, no IR spectral irradiation change was observed.

Photoluminescence of Amorphous Carbon Nitride (a-C:N) thin Films Grown by Facing Target Sputtering Method

Photoluminescence of Amorphous Carbon Nitride (a-C:N) thin Films Grown by Facing Target Sputtering Method

Investigation of Thin Film Properties of SiCN:H deposited by ECR PECVD with Acetylene and Ethane Hydrocarbon Sources

Silicon carbonitride (SiCN) thin films have drawn considerable interest among the ternary compounds due to the combination of unique properties such as high hardness, wide band gap, high photosensitivity in the ultraviolet (UV) region and low dielectric coefficient (k). In the last few decades various fabrication methods including reactive sputtering and plasma-enhanced chemical vapour deposition (PECVD) have been intensively studied to achieve SiCN thin films having attractive mechanical, tribological and optoelectronic features. Applications range from hard, wear-resistant coatings, low-k interconnects, UV photodetectors to gas separation membranes [1].The properties of thin films are not only influenced by the deposition method, which mainly determines the energy of bombarding ions, but also the choice of source gas [2]. In PECVD processes, silicon (Si), carbon (C) and nitrogen (N) can either be introduced separately as silane (SiH4), methane (CH4), and molecular nitrogen (N2) or ammonia (NH3), or alternatively using organic single precursors such as methylsilazanes [3]. In this work we deposited our thin films with the electron cyclotron resonance (ECR) PECVD method, which differs from other PECVD methods due to it is capability of generating a dense, highly ionized plasma (1011 ions/cm3) and ion impingement energies on the substrate as low as 20 eV [4]. We present the compositional and mechanical properties of hydrogenated SiCN (SiCN:H) thin films which were deposited with two different C precursors, acetylene (C2H2) and ethane (C2H6). The stoichiometry, density of the thin film, optical constants, and the bonding structure of SiCN:H thin films as a function of hydrocarbon carbon gas source have been explored. Due to the hydrogen-containing precursors used, the silicon carbonitride films deposited by CVD methods contain a significant amount of hydrogen (H). From Rutherford backscattering spectrometry (RBS), elastic recoil detection (ERD) analysis, quantitative elemental composition distributions including H were found for films deposited with both carbon sources. For further investigation of bonding structure of SiCN:H, Fourier Transform Infrared (FTIR) Spectroscopy and X-ray Photoelectron Spectroscopy (XPS) measurements were performed. Furthermore, we studied the hardness and Young’s modulus by nanoindentation, and variable angle spectroscopic ellipsometry (VASE) measurements were performed to extract optical constants. To interpret the measurements further, nearly stoichiometric silicon nitride and silicon carbide thin films were also prepared.[1] C.W. Chen, C.C. Huang, Y.Y. Lin, L.C. Chen, K.H. Chen, W.F. Su, Optical prop- erties and photoconductivity of amorphous silicon carbon nitride thin film and its application for UV detection, Diamond Relat. Mater. 14 (3-7) (2005) 1010–1013.[2] Schwarz-Selinger, T., Von Keudell, A., & Jacob, W. (1999). Plasma chemical vapor deposition of hydrocarbon films: The influence of hydrocarbon source gas on the film properties. Journal of Applied Physics, 86(7), 3988-3996.[3] V.I. Ivashchenko, A.O. Kozak, O.K. Porada, L.A. Ivashchenko, O.K. Sinelnichenko, O.S. Lytvyn, T.V. Tomila, V.J. Malakhov, Characterization of SiCN thin films: experimental and theoretical investigations, Thin Solid Films 569 (2014) 57–63.[4] M. G. Boudreau, "SiOxNy Waveguides Deposited by ECR-PECVD", M.Eng. thesis, McMaster University, 1993.

Effects of nitrogen incorporation on N-doped DLC thin film electrodes fabricated by dielectric barrier discharge plasma: Structural evolution and electrochemical performances

Hydrogenated amorphous carbon-nitride (a-C:H:N) thin films (or N-DLC) were deposited on glass and FTO substrates by a dielectric barrier discharge plasma technique using CH4/N2 gas mixture. The XPS results reveal that as the nitrogen ratio in the CH4:N2 gas mixture increases from 50% to 80%, the nitrogen doping level increased from 5.5 at.% to a maximum value of 11.5 at.% with especially high amounts of pyridinic (6.4 at %), and graphitic (4.7 at %) nitrogen. FEG-SEM results indicate a worm-like porous morphology for the 20%:80% CH4:N2 sample, relying on high amounts of pyridinic and graphitic N, which is a favorable structure to boost the ions diffusion process. This optimized N-DLC electrode with high nitrogen incorporation not only exhibits a nearly electrochemical reversibility with ΔEp (125 mV) and Jpa/Jpc (1.03) in K3Fe(CN)6 electrolyte, but also a fast charge transfer constant (6.59 × 10−4 cms−1). The excellent performance of this electrode is ascribed to the high nitrogen doping level, large surface area, the abundant holes, and the high nano-pore volume possessing excellent electron transfer ability for redox reaction. N-DLC thin film exhibits a promising prospect for biosensors and electrochemical electrode applications.

Effects of Electron Beam Treatment on Amorphous Carbon Nitride Thin Films Grown by Using the Facing Target Sputtering Method

Effects of Electron Beam Treatment on Amorphous Carbon Nitride Thin Films Grown by Using the Facing Target Sputtering Method

The optical band gap in amorphous carbon nitride thin films: Effect of sp2 hybridized C atoms configurations

In this paper, we employ the results of spectral measurements performed using XPS, Raman scattering and UV-VIS techniques to investigate the relationship between the optical band gap and the structural composition of amorphous carbon nitride thin films.From the point of view of the electronic structure of amorphous carbon nitride thin films with relatively high nitrogen content (N/C ≥ 0.1) the results have shown that the case where the C(sp2)–N and C(sp3)–N bonds concentrations are equal is an approach to the case of amorphous carbon (a-C), and therefore the optical band gap is controlled only by the π electron delocalization in C(sp2)–C bonds. This was demonstrated by investigating the direct proportion between Raman ratio ID/IG and 1/Eg2.

(Invited) Microfabrication and Electrochemical Activation of Amorphous Carbon Nitride a-CNx Working Electrode Integrated in Microfluidic Chip

a-CNx films are well-known polarizable interface materials with a large potential window (3 V-4 V [1]) interesting electrochemical reactivity [2] and tunable chemical surfacic composition [3]. Indeed, the surface structure, surface properties, number of grafting sites available are tunable according to the atomic percentage of nitrogen in the a-CNx [4]. High surface reactivity are highly dependent on the surface state and can be affected by synthesis (by varying the Csp3/sp2 ratio), and by pre-treatment (electrochemical or plasma). In this work, we elaborated a microfluidic chip integrating a-CNx as working microelectrodes. In brief, a titanium/ platinum (50/500 Å) underlayer was first deposited on the glass wafer and patterned as working microelectrodes for the future thin film a-CNx adhesion and conductivity. On the top of the working electrode, a 220 nm a-CNx (x=0.12), layer was deposited with DC magnetron sputtering (time =20 min, power=200 W) with a graphite target under a flow of nitrogen (PN2/Ptot =3%, Ptot =0.4 Pa). Then, a classical PDMS fluidic circuit was microfabricated and pre-treated with nitrogen plasma to favor its adhesion onto the glass slide containing the Ti/Pt/ a-CNx microelectrodes. The a-CNx microelectrodes were also electrochemically pre-treated in galvanostatic mode using 0.1 M KOH solution (anodic pre-treatment). The hydrodynamic properties of the fluidic channel a-CNx microelectrodes (as-grown and pre-treated) were screened with the [Fe(III)(CN)6]3−/[Fe(II)(CN)6]4− redox couple by cyclic voltammetry and impedance spectroscopy to provide a basis for further investigations such as the influence of a-CNx electrode pre-treatment on the DNA probe density issues in order to enhance the hybridization reaction efficiency with its specific DNA target. [1]. A. Lagrini, C. Deslouis, H. Cachet, M. Benlahsen, and S. Charvet. Elaboration and electrochemical characterization of nitrogenated amorphou scarbon films, Electrochem. commun., 6(3) (2004) 245–248. [2]. G Adamopoulos, C Godet, C Deslouis, H Cachet, A Lagrini, and B Saidani. The electrochemical reactivity of amorphous hydrogenated carbon nitrides for varying nitrogen contents: the role of the substrate. Diam. Relat. Mater.,12 (2003) 613– 617. [3]. R A Medeiros, A Benchick, R C Rocha-Filho, O Fatibello-Filho, B Saidani, C Debiemme-Chouvy, and C Deslouis. Simultaneous detection of ascorbic acid and dopamine with electrochemically pretreated carbon nitride electrodes: Comparison with boron-doped diamond electrodes. Electrochem. commun., 24 (2012) 61–64. [4]. M Faure, F Billon, A M Haghiri-Gosnet, B Tribollet, C Deslouis, A Pailleret, and J. Gamby. Influence of the atomic nitrogen content in amorphous carbon nitride thin films on the modulation of their polarizable interfaces properties. Electrochim. Acta, 280 (2018) 238-247.

Effect of Radio Frequency Power on a-CNx Film Properties and Its Performance as Humidity Sensors

A series of amorphous carbon nitride (a-CNx) thin films were deposited on silicon (111) substrates using a home-built radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) system. The a-CNx thin films were deposited from a mixture of a fixed flow-rate of ethane (C2H6, 20 sccm) and nitrogen (N2, 47 sccm) gases with varying RF power. A higher ratio of C to H (C to H ratio is 1:3) atoms in C2H6 as compared to the ratio in methane (CH4) gas (C to H ratio is 1:4) is expected to produce an interesting effect to the film properties as humidity sensor. The characterization techniques used to determine the morphology and chemical bonding of the thin films are field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The variation of morphology and the existence of nitrile band in these samples are correlated with the electrical properties of a-CNx thin films. Using humidity sensing system, the sensing performance of the samples was examined. It was found that the response of sensors towards the percentage of relative humidity (% RH) change is good resistive responses and good repeatability. The sensitivity of the prepared a-CNx thin films is significantly higher (up to 79%) as compared to previous studies using CH4 or acetylene as precursor gas. Based on these results, the properties and the sensitivity of the a-CNx thin films towards humidity can be tailored by using an appropriate precursor gases and deposition parameters.

Effects of deposition angle on synthesis of amorphous carbon nitride thin films prepared by plasma focus device

Amorphous carbon nitride (a-CNx) thin films were deposited on graphite substrate at different angular positions using a low energy (up to 4.9 kJ) Mather-type plasma focus device. The deposition processes were carried out during 20 focus shots at optimum nitrogen gas pressure of 0.4 mbar. The formation of amorphous carbon nitride was confirmed by Raman Spectroscopy, SEM, EDX, FTIR, and XRD analyses. The intensity ratio of D and G peaks (ID/IG) recorded by Raman Spectroscopy showed two distinct trends at various angular positions. The sample deposited at 30° had the highest ID/IG ratio and correspondingly the highest sp3 CHx content in FTIR spectrum. Samples with lower ID/IG ratio appeared with smaller grain size and more smooth surfaces in SEM images. The highest CN intensities in FTIR spectrum belonged to those samples deposited at 30 and 75° angular positions.

Structural, optoelectronic and mechanical properties of PECVD Si-C-N films: An effect of substrate bias

Structural, optoelectronic and mechanical properties of amorphous silicon carbon nitride (Si-C-N) thin films produced by plasma enhanced chemical vapor deposition (PECVD) at different negative substrate biases (Ud) are studied. The films are characterized by X-ray diffraction, atomic force microscopy, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, optical transmittance spectroscopy, nanoindentation as well using the results of the measurements of photoluminescence (PL) and PL excitation (PLE) spectra. All deposited films are found to be X-ray amorphous. An increase in Ud leads to: a smoothing of the film surface; a decrease of the transparency; an increase of refractive index from 1.69 to 1.92; a decrease of the energy gap from 4.15 to 2.38 eV; an increase in nanohardness and elastic modulus from 14 GPa to 24 GPa and from 147 GPa to 190 GPa, respectively. These results were explained in terms of the bonding configuration from XPS and FTIR measurements. The PL spectra of the films deposited at lower negative substrate bias have one PL band in the region between 530 and 540 nm, whereas the PL spectra of the films deposited at higher negative substrate bias show two PL bands at 530–570 nm and 640–650 nm. On the basis of the PLE data, it was shown that these PL bands are related to the electronic recombination between the conduction band and the valence bands and their tails within the amorphous N-rich and C-rich Si-C-N-O-H networks.

Tribological, electrochemical and biocompatibility properties of Ti6Al4V alloy produced by selective laser melting method and then processed using gas nitriding, CN or Ti-C:H coating treatments

Ti6Al4V alloy samples prepared by selective laser melting (SLM) were nitrided at a high temperature of 900 °C and then coated with amorphous carbon nitride (CN) or DLC-doped Ti (TiC:H) thin films using a closed field unbalanced magnetron sputtering (CFUMS) system. The microstructures, mechanical properties and coating adhesion strengths of the various specimens were evaluated by X-ray diffraction, nanoindentation tests and Rockwell hardness tests, respectively. The tribological properties of the samples were examined in 0.89 wt% NaCl solution by means of reciprocating sliding wear tests performed against 316L, Si3N4 and Ti6Al4V balls under a load of 10 N for 1440 s. In addition, the corrosion properties were evaluated by potentiodynamic polarization tests. Finally, cytotoxicity tests were performed using mouse leukemic monocyte macrophage cells (Raw 264.7) for culture periods of 1, 3 and 5 days, respectively. Overall, the Ti6Al4V sample processed using a duplex nitriding and DLC coating treatment exhibited a good coating adhesion, the highest wear resistance, the best corrosion resistance and excellent biocompatibility.

Influence of the atomic nitrogen content in amorphous carbon nitride thin films on the modulation of their polarizable interfaces properties

Amorphous carbon nitride (a-CNX) thin films possessing different nitrogen contents (0.12 ≤ x ≤ 0.30) have been synthetized by the DC cathodic reactive magnetron sputtering technique on transparent glass/indium tin oxide (ITO) substrates. They were characterized ex-situ by using two microscopy techniques: scanning electron microscopy (SEM) and atomic force microscopy (AFM), a spectroscopic technique: X-ray photoelectron spectroscopy (XPS), and in solution by using electrochemical methods: cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results obtained with these methods have permitted to highlight why a-CN0.30, the a-CNx sample with the highest nitrogen content among those investigated in this work, behaves both as a dielectrical material (low electronic conductivity) and as an ideally polarizable interface (high polarization resistance). For this purpose, the role of both the ionic strength and the overpotential were investigated in blocking electrode conditions, i.e. only in the presence of the supporting electrolyte. It was observed that the interfacial capacitance can be strongly electrically modulated with the ionic charge concentration and with the applied overpotential. The understanding of the behaviour of a-CNx materials presents a great challenge for their integration in new microfluidic transistor type devices in view of the elaboration of polarizable interface flow-field effect transistors (PI-FFETs).

Orientation of a Trametes versicolor laccase on amorphous carbon nitride coated graphite electrodes for improved electroreduction of dioxygen to water

Amorphous carbon nitride (a-CNx) thin films were used for the first time as electrode materials in the elaboration of biofuel cell cathodes as a consequence of i) the natural presence of amine type functional groups and ii) the ease to generate carboxylic acid groups on their surface with the help of an anodic treatment. Their rich surface chemistry was exploited to investigate the influence of the orientation of immobilised laccase on their bioelectrocatalytic activity towards oxygen reduction reaction (ORR) in a direct electron transfer configuration. Among four different immobilisation strategies leading to a statistical control of the orientation and tested in this work, spontaneous adsorption of natural laccase on pristine a-CNx provided the smallest current density value (3.5 μA cm−2) whereas covalent grafting of oxidised laccase on anodically treated a-CNx via imine and amide bond formation using a coupling agent led to a much higher but still low 44.6 μA cm−2 current density. This substantial improvement of the current density value measured for ORR confirms that the orientation of immobilised laccase exerts a measurable influence on its bioelectrocatalytic activity towards ORR.In parallel, the surface coverage rate of enzymes showing such activity was estimated as a function of the immobilisation method by using four different techniques (current density, activity towards ABTS, XPS and AFM). It was found that only a small fraction (7.1% to the most) of the electrode surface is covered with active enzymes, whatever the immobilisation method, whereas an enzyme population corresponding (almost) to a full enzyme monolayer was actually immobilised. This observation is crucial because it strongly suggests that the development of innovative immobilisation strategies allowing an increase of the active enzyme fraction through a simultaneous optimisation of the bioelectrocatalytic activity of the enzyme and of its electronic communication with the electrode offers much more promising perspectives than the control of the orientation of the immobilised enzyme population on its own.

Effect of nitrogen plasma afterglow on the surface charge effect resulted during XPS surface analysis of amorphous carbon nitride thin films

The aim of this paper is to investigate the relationship between the micro structure and the surface charge effect resulted during XPS surface analysis of amorphous carbon nitride thin films prepared by laser ablation method.The study results show that the charge effect coefficient (E) is not just a correction factor. We found that the changes in this coefficient value due to incorporation of nitrogen atoms into the carbon network are related to the spatial configurations of the sp2 bonded carbon atoms, order degree and sp2 clusters size. In addition, results show that the curve E vs. C(sp3)-N is a characteristic curve of the micro structure. This means that using this curve makes it easy to sorting the samples according to the micro structure (hexagonal rings or chains).

A thermal study of amorphous and textured carbon and carbon nitride thin films via transient grating spectroscopy

In this study, we are considering a novel way of growing carbon nitride (CN) films by using High Power Impulse Magnetron Sputtering (HiPIMS). Carbon and CN thin films were grown on silicon substrate with varying nanocrystalline texturing: some samples were amorphous while others were either nanocrystalline graphite (for the carbon sample) or fullerene-like (for the CN sample), with both samples having a graphitic nanostructure vertically ordered throughout the film. Their thermal diffusivity was computed using transient grating spectroscopy in order to compare the impact of the material's nanostructure on its thermal property as well as benchmarking the performance of CN. It was found that the thermal properties of carbon thin films were decreased when doped with nitrogen, which is attributed to the increased atomic disorder introduced by the nitrogen cross-linking, impacting the phonon propagation. The impact of nitrogen doping on thermal properties opens new avenues in engineering materials with tailored and varying thermal properties at the microscale.

Photomechanical response of amorphous carbon nitride thin films

Photomechanical response of amorphous carbon nitride thin films

Aging- and thermal-annealing effects on the vibrational- and microstructural-properties of PECVD grown hydrogenated amorphous silicon carbon nitride thin films

In this work, the hydrogenated amorphous silicon carbon nitride (a-SiCN:H) thin films were grown by PECVD from the discharge of silane (SiH4), methane (CH4) and nitrogen (N2) gases. Thereafter, the stability of the bonding and microstructural properties with respect to the effects of aging (under atmospheric environment) and thermal annealing (under low and high N2 flow-rates) were investigated by using Fourier transform infrared (FTIR) and micro Raman scattering techniques. Analyses on the as-prepared films showed that the SiH, Si-OH, CH and NH vibrational bonds were stable even through prolong aging while that of SiCN and CN bonds increased and SiN bonds decreased after aging. Meanwhile, low temperature annealing were found to improve the film structure due to the out-diffusion process of N atoms from weak SiN and CN bonds and migration of these N atoms to form strong SiN and CN bonds as well as restructuring of dangling bonds to form new SiC bonds. Additionally, the graphitic phase was more prominent in the film grown at low N2 flow-rate upon annealing, especially when annealed at low temperature. The CN bonds in the graphitic phase were found to be weak and released N atoms even when annealed at low temperature. However, high temperature annealing was shown to remove the graphitic phases in the film structure.

Deposition of amorphous carbon nitride films on flexible substrates by reactive sputtering for applications in light-driven active devices

Amorphous carbon nitride (a-CNx) thin films deposited by reactive sputtering have great potential for driving source applications of light-driven active devices. We demonstrate, for the first time, the photoinduced deformation of a-CNx deposited on flexible substrates, namely, poly(ethylene naphthalate) (PEN) films and transparent cellulose nanopaper. a-CNx films without delamination were obtained on both substrates. By decreasing the thickness of PEN films, the photoinduced deformation became extremely large. A light-driven pump was fabricated using a-CNx-coated PEN films, and then the pumping motion was observed up to 10 Hz. When a He–Ne laser traced the surface of a-CNx films deposited on the nanopaper, the sample moved to the opposite side of the laser spot. The motion involved repeated expansions and contractions similar to the motion of caterpillars occurring owing to the temporary photoinduced deformation of a-CNx films.