In this work, hydrogenated amorphous carbon (a-C:H) films were prepared by using a radio frequency (13.56 MHz) plasma enhanced chemical vapor deposition (PECVD) method at 220 degrees C. The influence of the annealing treatments on the microstructure and optical properties of the a-C:H films has been investigated. Raman and X-ray photo electron spectroscopy (XPS) results showed that the sp2 carbon fraction and sp2/sp3 ratio increase and sp3 carbon fraction decrease with increasing the annealing temperature. However, with increasing annealing temperature, the D and G peak positions and the G peak FWHM have no obvious changes. The spectroscopic ellipsometry suggested that the density, refractive index n and the extinction coefficient k of the as deposited film and the films annealed at 300 and 400 degrees C are not affected obviously by thermal annealing treatments. However, when the annealing temperature is higher than 400 degrees C, the films become high-density and opaque, meanwhile, the film thickness decrease significantly. The UV-VIS spectroscopy measurement indicated that the increase of sp2 fraction and graphitization features of the a-C: H films result in the decrease of the films transmission and optical band gap.

Hydrogenated amorphous silicon carbide (a-SiCx:H) films have been deposited by plasma enhanced chemical vapor deposition (PECVD) system with different radio-frequency (RF) powers. The microstructure and optical properties of the films deposited at different RF powers have been studied. The results show that the sp2/sp3 ratio and the average size of sp2-C rich domains increase while the hydrogen content and the density of sp2-C rich domains in the film decreases with increasing RF power. In addition, the sp2 carbon domains are observed by HR-TEM, and a possible photoluminescence (PL) mechanism is also suggested: the strong PL emission originates from radiative recombination of excitons within sp2-C rich domains and CSi/CC random network. As RF power increases, the change of the PL properties can be attributed to the influence of RF power on the sp2-C rich domains and the CSi/CC random network. The corresponding color coordinates of PL spectra also show that the film has great application potential in white light emission.

A new hydrogenated amorphous silicon carbide (a-SiCx:H) thin film with carbon nanostructure is grown through plasma enhanced chemical vapor deposition (PECVD) method. The structural evolution and growth mechanism of the as deposited a-SiCx:H thin film are explored and further discussed with different substrate temperatures. The results show that the structure of the a-SiCx:H thin film is a multiphase structure of carbon nanostructures embedded into C-Si-O(-H) amorphous matrix, and the carbon nanostructure is a spheroidal graphite-like structure. With increasing substrate temperature, the carbon nanostructure gradually grows up through incorporation with surrounding nanostructures. When the substrate temperature increases further to 300 degrees C, the ultrafine basic structure units of graphite are found within the carbon nanostructure. In addition, the disorder of the thin film first increases and then decreases with increasing substrate temperature, which give rise to band tail states among the pi-pi* band gap. The change of structure of as synthesized a-SiCx:H thin film with different substrate temperatures supports the sub-plantation model. Furthermore, a tunable optical band gap depended on structure of the carbon nanostructures is demonstrated at different substrate temperatures, which may bring about a potential of application.

Hydrogenated Si-rich silicon carbide (SixC1-x:H)/amorphous carbon (a-C:H) nano-multilayer films have been prepared by PECVD method with different silane mixture gas flow rates at 200 degrees C. The influence of the silane mixture gas flow rate on the chemical bonds, composition, microstructure, optical band gap and photoluminescence properties of the nano-multilayer films were studied by employing Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, high-resolution transmission electron microscopy (HRTEM), ultraviolet-visible (UV vis) and photoluminescence spectroscopy, respectively. The FTIR and UV-vis spectra demonstrated that the incorporation of more carbon atoms into the SixC1-x:H networks is the main reason for the increase of optical band gap of the nano-multilayer films with increase of silane mixture gas flow rate. The Raman and HRTEM showed that there is no any nano-particles in the nano-multilayer films. The photoluminescence mechanisms of the nano-multilayer films was shown to be mainly contributed by band-to-band recombination of the Si-rich SixC1-x:H layers.

C-rich hydrogenated amorphous silicon carbide (a-Si-1_C-x(x):H) thin films were grown from hydrogen diluted silane (SiH4) and methane (CH4) mixtures in a plasma-enhanced chemical vapor deposition (PECVD) system at different silane gas flow rates. The effects of Si content on the composition, microstructure and photoluminescence (PL) properties of the films have been systematically investigated by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), ultraviolet-visible (UV-Vis) transmittance and PL spectra. The multiphase structure of the grown films is confirmed as graphite-like sp(2)-C rich clusters embedded in a Si-C/C-C random network, and the diameter of the spherical sp(2)-C clusters is about 20-60 nm. As Si atoms are gradually incorporated into the films, they replace some C atoms in the Si-C/C-C random network, which results in an increase of structure disorder and brings large band tail states and narrow E-g. Furthermore, it is found that both the sp(3) Si-C/C-C random network and the sp(2) carbon clusters are the origin of the PL emission, and the PL properties can be tuned by changing the Si content and the sp(2) carbon clusters in the C-rich a-Si-1_C-x(x):H thin films. (C) 2018 Elsevier B.V. All rights reserved.

In this work, we reported a controllable preparation of nanoporous Ni3S2 films by a simple solvothermal-assisted sulfuration of nickel foam. The pore size can be easily adjusted by controlling the sulfuration time. Electrochemical tests show that the specific capacitance and the cycling performance of the Ni3S2 films were sensitive to their pore size. The Ni3S2 films with optimal pore size demonstrate a high specific capacitance (3.42 F/cm(2) at 1 mA/cm(2)) and excellent cycling stability (about 102% after 4250 cycles at 7.5 mA/cm(2)). By contrast, the Ni3S2 films with either too large or too small pore size show much lower capacitance and relatively worse cycling stability. An asymmetric supercapacitor by using the optimal Ni3S2 film as the positive electrode and activated carbon coated on Ni foam as the negative electrode was also successfully assembled, which exhibited a superior energy density of 41.8 Wh/kg at power density of 155 W/kg and a high capacitance retention of 76.6% after 2000 cycles. (C) 2017 Published by Elsevier B.V.

Hydrogenated amorphous carbon (a-C:H) thin films are deposited by plasma-enhanced chemical vapor deposition (PE-CVD) technique with different frequency (RF) powers at a low substrate temperature (fixed at 250°C). In this work, the composition, the types of chemical banding, carbon hybridization structure and optical properties of the a-C:H thin films have been studied by FTIR, XPS, UV–Vis spectrum and PL spectrum testing techniques. The results show that the hydrogen content and carbon hybridization structure play an important role in the evolution of photoluminescence (PL) properties with increasing RF power. It is found that with the decrease of sp3/sp2 ratio, the peak energy for main PL emissions peaks (mode 2) showed a red shift. PL emission intensity of the a-C:H thin films is influenced by the hydrogen content and carbon sp2 cluster. The enlargement of sp2 rich clusters and the increase of the hydrogen content will lead to an enhancement of PL emission intensity, which is a consequence that the domain of sp2 rich clusters creates more radiative recombination centers with the increase of RF power. Furthermore, different full width at half maximum (FWHM) of PL emissions peaks can be attributed to band-to-band recombination in various size sp2 rich clusters.