Laser Interaction with Tio 2 Nano Material Surface and Plasma Measurements (original) (raw)
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Atomic force microscopy (AFM) X-ray diffraction X-ray photoelectron spectroscopy (XPS) Nanostructured TiO 2 films on Si (100) substrates have been grown by nanosecond pulsed laser deposition at the wavelengths of 266, 355 and 532 nm using a Q-switched Nd:YAG laser and TiO 2 sintered rutile targets. The effect of laser irradiation wavelength, the temperature of the substrate and the presence of O 2 as background gas on the crystallinity and surface structure of deposits were determined, together with the composition, expansion dynamics and thermodynamic parameters of the ablation plume. Deposits were analyzed by X-ray photoelectron spectroscopy, X-ray diffraction, environmental scanning electron microscopy and atomic force microscopy, while in situ monitoring of the plume was carried out and characterized with spectral, temporal and spatial resolution by optical emission spectroscopy. Stoichiometric, crystalline deposits, with nanostructured morphology were obtained at substrate temperatures above 600 °C. Microscopic particulates were found overimposed on the nanostructured films but their size and density were significantly reduced by operating at short wavelength (266 nm) and upon addition of a low pressure of oxygen (0.05 Pa). The dominant crystalline phase is rutile at 355 and 532 nm. At the short irradiation wavelength, 266 nm, the preferred phase in the presence of oxygen is rutile, while anatase is preferably observed under vacuum. The narrowest size distribution and smallest nanoparticle diameters, of around 25 nm, were found by deposition at 266 nm under 0.05 Pa of oxygen.
Optical emission spectroscopic studies on laser ablated TiO 2 plasma
Applied Surface Science, 2009
Optical emission spectroscopic investigations of the plasma produced during Nd:YAG laser ablation of sintered TiO 2 targets, in oxygen and argon gas environments are reported. The spatial variations of electron temperature (T e ) and electron number density (N e ) are studied. The effect of oxygen/argon pressure on electron temperature (T e ) and electron number density (N e ) is presented. The kinematics of the emitted particles and expansion of plume edge are discussed. Spatio-temporal variations of various species in TiO 2 plasma were recorded and corresponding velocities were calculated. The effect of oxygen pressure on intensity of neutral/ion species and their corresponding velocities is also reported. ß
Spectral Characterization of Laser Induced Plasma from Titanium Dioxide
Plasma Science and Technology, 2007
Optical emission from TiO2 plasma, generated by a nanosecond laser is spectroscopically analysed. The main chemical species are identified and the spatio-temporal distribution of the plasma parameters such as electron temperature and density are characterized based on the study of spectral distribution of the line intensities and their broadening characteristics. The parameters of laser induced plasma vary quickly owing to its expansion at low background pressure and the possible deviations from local thermodynamic equilibrium conditions are tested to show its validity.
Surface Etching of TiO2Thin Films Using High Density Cl2/Ar Plasma
Transactions on Electrical and Electronic Materials, 2015
In this study, we carried out an investigation of the etch characteristics of TiO 2 thin films and the selectivity of TiO 2 to SiO 2 in adaptive coupled C1 2 /Ar plasma. The maximum etch rate of the TiO 2 thin film was 136±5 nm/min at a gas mixing ratio of C1 2 /Ar (75%:25%). The X-ray photoelectron spectroscopy (XPS) analysis showed the efficient destruction of oxide bonds by the ion bombardment as well as the accumulation of low volatile reaction products on the etched surface.
Influence of auxiliary plasma source and ion bombardment on growth of TiO2 thin films
Surface and Coatings Technology, 2011
By inserting an auxiliary rf plasma source in an experimental setup for depositing TiO 2 thin films with a cathodic vacuum arc and high voltage pulses, i.e. metal plasma immersion ion implantation & deposition (MePIIID), it is shown that this auxiliary plasma source can increase the growth rate at low gas flow ratios only but not increase the oxygen/titanium ratio. It can be surmised that the plasma source creates activated oxygen species which are otherwise supplied from collisions of the titanium plasma stream with the background gas at higher pressures.
Surface chemistry and optical property of TiO 2 thin films treated by low-pressure plasma
Journal of Solid State Chemistry, 2007
The low temperature RF plasma treatment was used to control the surface chemistry and optical property of TiO 2 thin films deposited by RF magnetron sputtering with a very good uniformity at 300 1C substrate heating temperature. The XRD pattern indicates the crystalline structure of the film could be associated to amorphous structure of TiO 2 in thin film. The plasma treatment of TiO 2 film can increase the proportion of Ti 3+ in Ti2p and decrease in carbon atoms as alcohol/ether group in C1s at the surface. The optical transmittance of the film was enhanced by 50% after the plasma treatment. The surface structure and morphology remain the same for untreated and low-pressure plasma-treated films. Therefore, increase in the optical transmission could be due to change in surface chemistry and surface cleaning by plasma treatment. r
Journal of The Electrochemical Society, 2007
TiO 2 thin films have been prepared at temperatures between 298 and 523 K by plasma enhanced chemical vapor deposition at working pressures of 4 ϫ 10 −3 and 4 ϫ 10 −4 Torr, in this latter case by using electron cyclotron resonance conditions. Ti isopropoxide has been used as the precursor and oxygen or mixtures of oxygen + argon as the plasma gas. The refraction indexes of the films ͑from 1.95 to 2.4͒ have been correlated with their microstructure and surface roughness as observed, respectively, by scanning electron microscopy and atomic force microscopy. Optical emission spectroscopy analysis of plasma indicates a higher fragmentation of the precursor in a plasma of pure O 2 than in another of Ar + O 2 . Heating at T Ͼ 503 K induces the crystallization of the films into the anatase structure. The differences in the structure, microstructure, and optical properties are accounted for by assuming that the type of interactions of the plasma species with the growing film change with the deposition conditions.
Pulsed laser deposition of TiO2-2008.pdf
Promising applications of TiO 2 nanostructures include the development of optical devices, sensors, photocatalysts and self-cleaning coatings. In view of their importance, research on the synthesis of nanosized TiO 2 is a particularly active field. In this work we report on the investigation of the effect of laser irradiation wavelength (Q-switched Nd:YAG laser at 532, 355 and 266 nm), the temperature of the substrate and the atmosphere of deposition (vacuum, Ar and O 2 ) that are suitable for obtaining nanostructured deposits from TiO 2 sintered targets. The ablation plume emission is characterized with spectral and temporal resolution by optical emission spectroscopy (OES), while the surface morphology and chemical states of the material deposited on a Si (100) substrate are examined by environmental scanning electron microscopy (ESEM) and atomic force microscopy (AFM) and by X-ray photoelectron spectroscopy (XPS), respectively. Deposits with nanostructured morphology with grain size down to 40 nm and keeping the stoichiometry of the targets were obtained at high temperature, while the highest concentration of particulates was observed at the longest laser wavelength of 532 nm on a substrate heated up to 650°C. In situ characterization of the ablation plume, carried out by OES, indicated the presence of emissions assigned to Ti I, Ti II and O I. PACS 81.15.Fg · 68.55.-a · 61.82.Fk
Surface state of TiO 2 treated with low ion energy plasma
Applied Surface Science, 2006
The effect of low pressure radio frequency (rf) plasma treatment on TiO 2 surface states has been studied using X-ray photoelectron spectroscopy. Three different oxidation states of oxygen in untreated TiO 2 powder were observed, which suggests the existence of adsorbed water and carbon on the surface. The ratio of oxygen to titanium (O/Ti) was decreased for the low ion dose plasma treated samples due to desorption of water from the surface. In the case of Ti 2p about 20% of surface states were converted to Ti 3+ 2p 3/2 state after plasma treatment with a very good stability, whereas untreated TiO 2 remained mostly as Ti 4+ state. A rapid decrease in the ratio of carbon to titanium (C/Ti) at TiO 2 surface was also observed after plasma treatment and more than 90% of carbon atoms were removed from the surface. Therefore, the plasma treatment of TiO 2 has advantages to surface carbon cleaning, increasing O À and Ti 3+ surface states, hence improving the activity of TiO 2 for different environmental, energy and biological applications. #