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1.
Nitrogen-doped titanium oxide (TiOxNy) films were prepared with ion-assisted electron-beam evaporation. The nitrogen (N) incorporated in the film is influenced by the N2 flux modulated by the N2 flow rate through an ion gun. The TiOxNy films have the absorption edge of TiO2 red-shifted to 500 nm and exhibit visible light-induced photocatalytic properties in the surface hydrophilicity and the degradation of methylene blue. The structures and states of nitrogen in the films are investigated by X-ray diffraction patterns (XRD), and X-ray photoelectron spectroscopy (XPS) and related to their visible light-induced photocatalytic properties. The results indicate that the substitutional N in anatase TiO2 can induce visible light photocatalysis. The substitutional N is readily doped by the energetic nitrogen ions from the ion gun. The best photocatalytic activity is obtained at the largest N loading about 5.6 at.%, corresponding to the most substitutional N in anatase TiO2. The film exhibits the degradation of methylene blue with a rate-constant (k) about 0.065 h−1 and retaining 7° water contact angle on the surface under visible light illumination.  相似文献   

2.
Y.D. Su 《Applied Surface Science》2009,255(18):8164-8170
We deposit ternary WCxNy thin films on Si (1 0 0) substrates at 500 °C using direct current (DC) reactive magnetron sputtering in a mixture of CH4/N2/Ar discharge, and explore the effects of substrate bias (Vb) on the intrinsic stress, preferred orientation and phase transition for the obtained films by virtue of X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and selective area electron diffraction (SAED). We find that with increasing the absolute value of Vb up to 200 V the carbon (x) and nitrogen (y) atom concentrations of WCxNy films keep almost constant with the values of 0.75 and 0.25, respectively. The XPS and SAED results, combined with the density-functional theory (DFT) calculations on the electronic structure of WC0.75N0.25, show our obtained WCxNy films are single-phase of carbonitrides. Furthermore, we find that the compressive stress sharply increases with increasing the absolute value of Vb, which leads to a pronounced change in the preferred orientation and phase structure for the film, in which a phase transition from cubic β-WCxNy to hexagonal α-WCxNy occurs as Vb is in the range of −40 to −120 V. In order to reveal the relationship between the stress and phase transition as well as preferred orientation, the DFT calculations are used to obtain the elastic constants for β-WCxNy and α-WCxNy. The calculated results show that the preferred orientation is dependent on the competition between strain energy and surface energy, and the phase transition can be attributed to a decrease in the strain energy.  相似文献   

3.
Nanocrystalline multiphase titanium oxycarbide (TiCxOy) thin films composed of TiC2, TiO0.325, Ti2O3 and graphitic carbon have been deposited on titanium substrates, using energetic carbon ions delivered by the UNU/ICTP and the NX2 plasma focus devices operated at different repetition rates. X-ray diffraction (XRD) patterns of the nanocomposite films reveal the relative transformation of various oxide and carbide phases accompanied by the suppression of the TiC2 phase when the energy flux of the ion beam and the repetition rate are increased. A field emission scanning electron microscope (FESEM) with an energy dispersive X-ray spectroscopy (EDS) attachment reveals a non-porous microcrack-free nanocrystalline granular surface morphology of the composite films with uniform carbon distribution. X-ray photoelectron spectroscopy (XPS) confirms the formation of oxycarbides (TiCxOy) along with significant carbon adsorbate. Raman studies of the films also verify the relative phase transformation in the TiCxOy nanocomposite by tuning the deposition parameters. The Vickers microhardness of the sample surface is improved more than 400%. PACS 52.59.Hq; 52.77.Dq; 68.55.Jk; 81.15.-z; 81.65.Lp  相似文献   

4.
High-quality thin films of ZrN, ZrxAlyN and ZrxGayN have been grown by pulsed reactive crossed-beam laser ablation using Zr, Zr-Al and Zr-Ga ablation targets, respectively, and a N2 gas pulse. The films were characterized for their chemical, crystallographic and tribological properties. All the films had very low impurity levels and a cubic rock salt crystal structure over the entire investigated temperature range between room temperature and 600 °C. High-quality epitaxial films could be grown on Si (001) at 400 °C, though the crystallinity was disrupted at 525 °C by Si diffusion into the film bulk and the formation of ZrSi2 crystallites. Films grown on stainless steel were polycrystalline. The ratios of the metals in the alloy targets were in general not equal to those in the films: the Al content in the ZrxAlyN films was lower than the target value, which we attribute to differential scattering in the ablation plume. The Ga content in the ZrxGayN films fell with increasing substrate temperature, indicative of re-evaporation of Ga from the substrate surface. Those ZrxGayN films with the highest Ga content, grown at the lowest temperatures, were particularly nitrogen-deficient, which we attribute to the low reactivity of Ga with N2. The ZrxAlyN films had an exceptionally low coefficient of friction (0.20) versus steel and the greatest nanohardness of 28 GPa. Received: 9 November 2000 / Accepted: 14 November 2000 / Published online: 28 February 2001  相似文献   

5.
Lei Zhao 《Applied Surface Science》2008,254(15):4620-4625
Nitrogen-doped titanium dioxide (TiO2−xNx) thin films have been prepared by pulse laser deposition on quartz glass substrates by ablated titanium dioxide (rutile) target in nitrogen atmosphere. The x value (nitrogen concentration) is 0.567 as determined by X-ray photoelectron spectroscopy measurements. UV-vis spectroscopy measurements revealed two characteristic deep levels located at 1.0 and 2.5 eV below the conduction band. The 1.0 eV level is attributable to the O vacancy state and the 2.5 eV level is introduced by N doping, which contributes to narrowing the band-gap by mixing with the O2p valence band. The enhanced degradation efficiency in a broad visible-light range was observed from the degradation of methylene blue and methylene orange by the TiO2−xNx film.  相似文献   

6.
In this study, TiO2−xNx/TiO2 double layers thin film was deposited on ZnO (80 nm thickness)/soda-lime glass substrate by a dc reactive magnetron sputtering. The TiO2 film was deposited under different total gas pressures of 1 Pa, 2 Pa, and 4 Pa with constant oxygen flow rate of 0.8 sccm. Then, the deposition was continued with various nitrogen flow rates of 0.4, 0.8, and 1.2 sccm in constant total gas pressure of 4 Pa. Post annealing was performed on as-deposited films at various annealing temperatures of 400, 500, and 600 °C in air atmosphere to achieve films crystallinity. The structure and morphology of deposited films were evaluated by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and atomic force microscopy (AFM). The chemical composition of top layer doped by nitrogen was evaluated by X-ray photoelectron spectroscopy (XPS). Photocatalytic activity of samples was measured by degradation of Methylene Blue (MB) dye. The optical transmittance of the multilayer film was also measured using ultraviolet-visible light (UV-vis) spectrophotometer. The results showed that by nitrogen doping of a fraction (∼1/5) of TiO2 film thickness, the optical transmittance of TiO2−xNx/TiO2 film was compared with TiO2 thin film. Deposited films showed also good photocatalytic and hydrophilicity activity at visible light.  相似文献   

7.
To use solar irradiation or interior lighting efficiently, we sought a photocatalyst with high reactivity under visible light. Nitrogen and carbon doping TiO2−xyNxCy films were obtained by heating the TiO2 gel in an ionized N2 gas and then were calcined at 500 °C. The TiO2−xyNxCy films have revealed an improvement over the TiO2 films under visible light (wavelength, 500 nm) in optical absorption and photocatalytic activity such as photodegradation of methyl orange. X-ray photoemission spectroscopy, infrared spectrum and UV-visible (UV-vis) spectroscopy were used to find the difference of two kinds of films. Nitrogen and carbon doped into substitutional sites of TiO2 has been proven to be indispensable for band-gap narrowing and photocatalytic activity.  相似文献   

8.
Amorphous silicon oxycarbonitride thin films were synthesized on polyethylene terephthalate (PET) substrates at low temperatures (~80 °C) by plasma-enhanced chemical vapor deposition (PECVD). A high ion flux and suitable nitrogen flow rate improved the gas barrier properties and deposition rate of the resulting a-SiOxCyNz film. The a-SiOxCyNz films were deposited at a high deposition rate and low water WVTR properties as a result of the high ion flux and nitrogen chemistry. The high ion flux modified the chemical structure and nitrogen atomic composition of the resulting a-SiOxCyNz film coatings. The substrate temperature was characterized using a thermometer. In addition, the coating properties were characterized by Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS) and the water vapor transmission rate (WVTR).  相似文献   

9.
ZrOxNy thin films have been prepared by radio frequency magnetron sputtering at various substrate temperatures. The effect of substrate temperature on structural, optical properties and energy-band alignments of as-deposited ZrOxNy thin films are investigated. Atomic force microscopy results indicate the decreased root-mean-square (rms) values with substrate temperature. Fourier transform infrared spectroscopy spectra indicate that an interfacial layer has been formed between Si substrate and ZrOxNy thin films during deposition. X-ray photoelectron spectroscopy and spectroscopy ellipsometry (SE) results indicate the increased nitrogen incorporation in ZrOxNy thin films and therefore, the decreased optical band gap (Eg) values as a result of the increased valence-band maximum and lowered conduction-band minimum.  相似文献   

10.
TiO2 and TiO2/ZnO double layer films were sputtered on glass substrates. It was found that a thin ZnO underlayer is helpful for tailoring the microstructure and surface morphology of the TiO2 film. By applying a 70-nm-thick ZnO underlayer, a TiO2 thin film of 100 nm in thickness with well crystallized anatase phase and rough surface was successfully fabricated without heating the substrate. Relatively high photo-catalytic activity and good hydrophilic properties were observed in such TiO2/ZnO double layer films.  相似文献   

11.
Hafnium oxynitride (HfOxNy) gate dielectric has been deposited on Si (1 0 0) by means of radio frequency (rf) reactive sputtering using directly a HfO2 target in N2/Ar ambient. The thermal stability and microstructural characteristics for the HfOxNy films have been investigated. XPS results confirmed that nitrogen was successfully incorporated into the HfO2 films. XRD analyses showed that the HfOxNy films remain amorphous after 800 °C annealing in N2 ambient. Meanwhile the HfOxNy films can also effectively suppress oxygen diffusion during high temperature annealing and prevent interface layer from forming between HfOxNy films and Si substrates. AFM measurements demonstrated that surface roughness of the HfOxNy films increase slightly as compared to those pure HfO2 films after post deposition annealing. By virtue of building reasonable model structure, the optical properties of the HfOxNy films have been discussed in detail.  相似文献   

12.
Thin films of the Nd1+x Ba2?x Cu3Oy high-T c superconductor (NBCO) with different neodymium/barium ratios have been obtained by laser ablative cosputtering of targets with different elemental compositions. The films with excess neodymium (x>0) had a low surface particle density and were rough, but their critical temperature decreased with increasing x. Conversely, barium-rich films (x<0) exhibited independence of the superconducting properties of the film composition, with an appreciable number of particles observed on the surface. Substitution of Ba for Nd in NBCO thin films is apparently impeded, so that excess barium precipitates in the form of (Ba,Cu)Oz particles. The structure and superconducting properties of NBCO reveal a strong dependence on the conditions of film saturation by oxygen.  相似文献   

13.
CuInxGa1−xSeyS2−y (CIGS) thin films were synthesized on glass substrates by a paste coating of Cu, In, and Ga precursor solution with a three-step heat treatment process: oxidation, sulfurization, and selenization. In particular, morphological changes of CIGS films for each heat treatment step were investigated with respect to the kinds of glass substrates: bare, Mo-coated, and F-doped SnO2 (FTO) soda-lime glasses. Very high quality CIGS film with large grains and low degree of porosity was obtained on the bare glass substrate. Similar morphology of CIGS film was also acquired on the Mo-coated glass except the formation of an undesired Mo oxide interfacial layer due to the partial oxidation of Mo layer during the first heat treatment under ambient conditions. On the other hand, CIGS film with much smaller grains and higher degree of porosity was gained when FTO glass was used as a substrate, resulting in slight solar to electricity conversion behavior (0.20%). Higher power conversion efficiency (1.32%) was attained by the device with the CIGS film grown on Mo-coated glass in spite of the presence of a Mo oxide impurity layer.  相似文献   

14.
HfNxOy thin films were deposited on Si substrates by direct-current sputtering. The influence of N2 ambient annealing on the morphology, structure and field emission properties of the HfNxOy thin films was studied systematically. Scanning electron microscopy indicates that both the as-deposited and the annealed films are composed of nanoparticles, and the particle sizes of these films do not change much before and after annealing. Atomic force microscopy shows that the surface of the as-deposited films is smooth while that of the annealed films becomes rough, with many protrusions. X-ray diffraction patterns demonstrate that the as-deposited films are amorphous while the samples annealed at over 500 °C are polycrystalline. It is found that the field electron emission properties of the annealed films are better than those of the as-deposited films. The film annealed at 800 °C shows the best field emission properties. The mechanism for the improvement of the field electron emission property of the annealed thin films is also discussed. PACS 73.61.-r; 79.70.+q; 81.05.-t  相似文献   

15.
ZrNx films were sputtered in an Ar + N2 atmosphere, with different substrate biases (0 to −200 V) at various nitrogen flow ratios (%N2 = 0.5-24%). The surface morphology, resistivity, crystllinity, and bonding configuration of ZrNx films, before and after vacuum annealing, were investigated. As compared with ZrNx films grown without substrate bias, before and after annealing, the resistivity of 1% and 2% N2 films decreases with increasing substrate biases. Simultaneously, if the applied bias is too high, the crystallinity of ZrNx film will decrease. The surfaces of 1% and 2% N2 flow films deposited without bias have small nodules, whereas the surface morphology of films deposited at −100 V of substrate bias exhibits large nodules and rugged surface. Once a −200 V of substrate bias is applied to the substrate, the surface morphology of ZrNx films, grown at 1% and 2% nitrogen flow ratios, is smooth. Furthermore, there are two deconvoluted peaks in XPS spectra (i.e., Zr-O and Zr-N) of ZrNx films deposited at −200 V of substrate bias before and after annealing. On the other hand, the surface morphology changes dramatically from rugged surfaces for film deposited at lower nitrogen flow ratio (%N2 < 1%) to smoother and denser surfaces for film grown at higher nitrogen flow ratio (%N2 ≥ 1%). The Zr-N bonding in 2% N2 films still exist after annealing at 700 °C, while the Zr-N bonding in 0.5% and 16% N2 flow film vanish at the same temperature. The connection between the resistivity, crystallinity, surface morphology, and bonding configuration of ZrNx films and how they are influenced by the substrate bias and nitrogen flow ratio are discussed in this paper.  相似文献   

16.
The characteristics of InOx Ny alloy films prepared via thermal oxidation of InN epitaxial films with In‐ or N‐polarities grown on nearly lattice‐matched, yttria‐stabilized zirconia (YSZ) substrates are investigated. The InN films were oxidized to InOx Ny with a gradual change in O/N composition by annealing in air. Structural analysis revealed that the temperature for phase transition from wurtzite structure depends on the polarity of InN, and N‐polar InOx Ny films can retain their wurtzite structure even at higher temperatures compared with the case of In‐polar films. Furthermore, changes in the valence band structure and optical characteristics of the InOx Ny alloys take place via thermal oxidation. These results indicate that InOx Ny grown via thermal oxidation of N‐polar InN on YSZ can be considered as an alloy semiconductor for optoelectronic devices. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

17.
Plasma-enhanced chemical vapor deposition was used to conformally coat commercial TiO2 nanoparticles to create nanocomposite materials. Hexamethyldisiloxane (HMDSO)/O2 plasmas were used to deposit SiO2 or SiOxCyHz films, depending on the oxidant concentration; and hexylamine (HexAm) plasmas were used to deposit amorphous amine-containing polymeric films on the TiO2 nanoparticles. The composite materials were analyzed using Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). These analyses reveal film composition on the nanoparticles was virtually identical to that deposited on flat substrates and that the films deposit a conformal coating on the nanoparticles. The performance of the nanocomposite materials was evaluated using UV-vis spectroscopy to determine the dispersion characteristics of both SiOx and HexAm coated TiO2 materials. Notably, the coated materials stay suspended longer in distilled water than the uncoated materials for all deposited films.  相似文献   

18.
The initial stages in the growth of BaxSr1?xTiO3 films on various dielectric substrates were studied using the middle-energy ion scattering spectroscopy, and the results obtained were used to analyze microdefects in the film. The character of film growth was found to depend on the shape, size, and electrostatic state of crystallographic unit cells of the substrate surface. The growth was epitaxial on an SrTiO3 substrate. The film prepared on an LaAlO3 substrate consists of slightly disordered crystallites. Films on MgO substrates demonstrated island-type growth up to a thickness of 20 nm, with foreign phases observed to form; as the film thickness increased, the growth acquired an epitaxial pattern. The film grown on the \(\alpha - Al_2 O_3 (1\bar 102)\) surface was polycrystalline and contained textured blocks.  相似文献   

19.
Thickness and chemical composition of the TiNxOy thin films deposited by reactive magnetron sputtering from Ti target at controllable oxygen flow rate were determined by Rutherford Backscattering Spectroscopy (RBS) using 2 MeV He+ ions. The films were deposited on carbon foils and amorphous silica (a-SiO2) substrates at 25 °C and 250 °C. The estimated film thickness is of 75-100 nm. The O/Ti atomic ratio in the films increases up to 1.5 with increasing oxygen flow rate, while that of N/Ti decreases from about 1.1 for TiN to 0.4 at the highest oxygen flow rate. Substantial out-diffusion of carbon from the substrate is observed which is independent of the substrate temperature. Films grown onto a-SiO2 substrates can be treated as homogeneous single layers without interdiffusion. It is more difficult to determine the nitrogen and oxygen content due to superposition of RBS signals arising from film and substrate. RBS analysis of the depth profile indicates that for the investigated films the carbon diffusion and oxidation not only at the topmost surface layers but over the bulk of the films were found. Comparison with XPS results indicates substantial oxygen adsorption at the surface of TiNx thin films obtained at zero oxygen flow rate.  相似文献   

20.
TiO2 films were prepared on a silicon or soda-glass substrate using a sol suspension. The TiO2 film on the silicon substrate was composed of pure anatase phase and showed almost no contaminations. In contrast, the TiO2 film on the soda-glass substrate was composed of anatase and brookite phases. The diffusion of Na into the TiO2 film on the soda-glass substrate was observed by XPS, and Na was concentrated on the surface of the film. The yield of the brookite phase increased with decreasing distance from the surface of the film on the soda-glass substrate. Na promoted the formation of the brookite phase, although the preparative procedure was used for anatase synthesis.  相似文献   

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