• Journal of the Korean institute of surface engineering
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• v.34 no.3
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• pp.258-263
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• 2001

Siloxane thin films were fabricated on a silicon wafer by spin-coating using a siloxane solution made by the sol-gel process. Fluorine was doped using$ CF_4$ plasma treatment. The film was then annealed in-situ state in the nitrogen atmosphere. In order to examine the influence of annealing and fluorine doping on the siloxane thin film, thermogravimetric-differential thermal analysis (TG-DTA), Fourier transform-infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) were used and the dielectric constant was determined by the high-frequency capacitance-voltage method. Stable siloxane films could be obtained by in-situ annealing in a nitrogen atmosphere after $CF_4$ plasma treatment, and the dielectric value of the film was $\varepsilon$ 2.5.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.204.2-204.2
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• 2013

Wide band gap II-VI semiconductors have attracted the interest of many research groups during the past few years due to the possibility of their applications in light-emitting diodes and laser diodes. Among the II-VI semiconductors, ZnO is an important optoelectronic device material for use in the violet and blue regions because of its wide direct band gap (Eg ~3.37 eV) and large exciton binding energy (60 meV). F-doped ZnO (FZO) and undoped ZnO thin films were grown onto quartz substrate by the sol-gel spin-coating method. The doping level in the solution, designated by F/Zn atomic ratio of was varied from 0 to 5 in 1 steps. To investigate the effects of the structure and optical properties of FZO thin films were investigated using X-ray diffraction (XRD), UV-visible spectroscopy, and photoluminescence (PL). In the XRD, the residual stress, FWHM, bond length, and average grain size were changed with increasing the doping concentration. For the PL spectra, the high INBE/IDLE ratio of the FZO thin films doping concentration at 1 at.% than the other samples.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.142.2-142.2
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• 2013

The effect of substrate on catalytic activity of CO oxidation with transition metal Platinum nanoparticles on doped and undoped TiO2 was investigated. Titanium dioxide was doped chemically with non-metal anions including nitrogen and fluorine. Undoped TiO2 was synthesized via simple conventional sol-gel route. Thin films of titania were developed by spin coating technique and the characterization techniques SEM, XRD, UV-Vis Absorption Spectroscopy and XPS were carried out to examine the morphology of films, crystal phase, crystallites, optical properties and elemental composition respectively. XPS analysis from doped TiO2 confirmed that the nitrogen site were interstitial whereas fluorine was doped into TiO2 lattice substitutionally. Catalytic activity systems of Pt/doped-TiO2 and Pt/undoped-TiO2 were fabricated to reveal the strong metal-support interaction effect during catalytic activity of CO oxidation reactions. By arc plasma deposition technique, platinum nanoparticles with mean size of 2.7 nm were deposited on the thin films of doped and undoped titanium dioxide. The CO oxidation was performed with 40 Torr CO and 100 Torr O2 with 620 Torr He carrier gas. Turn over frequency was observed two to three folds enhancement in case of Pt/doped TiO2 as compared to Pt/TiO2. The electronic excitation and the oxygen vacancies that were formed with the doping process were the plausible reasons for the enhancement of catalytic activity.

• Applied Chemistry for Engineering
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• v.32 no.6
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• pp.632-639
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• 2021

In this research, fluorine doping was performed to enhance the photocatalytic activities of WO₃ which were measured using methylene blue dye. WO_3-xF_x photocatalyts were prepared by a vaper phase fluorination during a sintering for preparing WO₃ photocatalysts from a WCl₆ precursor. The bandgap energy of WO₃ photocatalysts decreased from 2.95 eV to 2.54 eV, and the oxygen vacancies site increased by about 55% after fluorine doping. In addition, the initial degradation efficiency of methylene blue showed that the fluorine doped sample showed a 6-fold increase in photocatalytic activities from 10% to 60% compared to that of the untreated sample. It is believed that fluorine is doped to reduce the band gap of photocatalysts, enabling the catalytic activity with low energy, and that oxygen vacancies-generated surface defects increase the visible light absorption region of WO₃ photocatalysts, thereby increasing photocatalytic activity. In this study, it was confirmed that fluorine-doped WO_3-xF_x photocatalysts with an excellent photocatalytic activity can be manufactured easily using a one-step vaper phase fluorination that does not require a post-treatment process.

• Journal of Electrochemical Science and Technology
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• v.8 no.4
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• pp.338-343
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• 2017

Activated carbon has lower electrical conductivity and reliability than other carbonaceous materials because of the oxygen functional groups that form during the activation process. This problem can be overcome by doping the material with heteroatoms to reduce the number of oxygen functional groups. In the present study, N, F co-doped activated carbon (AC-NF) was successfully prepared by a microwave-assisted hydrothermal method, utilizing commercial activated carbon (AC-R) as the precursor and ammonium tetrafluoroborate as the single source for the co-doping of N and F. AC-NF showed improved electrical conductivity ($3.8\;S\;cm^{-1}$) with N and F contents of 0.6 and 0.1 at%, respectively. The introduction of N and F improved the performance of the pertinent supercapacitor: AC-NF exhibited an improved rate capability at current densities of $0.5-50mA\;cm^{-2}$. The rate capability was higher compared to that of raw activated carbon because N and F codoping increased the electrical conductivity of AC-NF. The developed method for the co-doping of N and F using a single source is cost-effective and yields AC-NF with excellent electrochemical properties; thus, it has promising applications in the commercialization of energy storage devices.

• Journal of the Korean Ceramic Society
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• v.43 no.11 s.294
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• pp.738-742
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• 2006

We report on the effects of co-doping with fluorine on properties of ZnO thin films grown by pulsed-laser deposition. The transport characteristics of Ag-F and Li-F codoped ZnO films were determined by Hall-effect measurements at room temperature. Ag-F codoped ZnO films showed n-type semiconducting behaviors. An ambiguous carrier type was observed in Li-F codoped ZnO films grown at a temperature of 500$^{\circ}C$ with the oxygen pressures of 20 and 200 mTorr. The qualities of the codoped ZnO films were studied by X-ray diffraction, atomic force microscopy, X-ray photoemission spectroscopy, and photoluminescence.

• Applied Chemistry for Engineering
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• v.33 no.2
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• pp.159-165
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• 2022

To enhance the photocatalytic activities of WO₃ photocatalysts, fluorine doping was performed to induce the oxygen vacancies. Both plasma and direct vaper fluorination were carried out for fluorine doping, and photocatalytic activities were examined by using methylene blue dye. Oxygen vacancies of the plasma and direct vaper fluorinated WO₃ photocatalysts were measured to be 14.65 and 18.59%, which increased to about 23 and 56% at pristine WO₃ photocatalysts. The degradation efficiency of methylene blue was also determined about 1.7 and 3.4 times higher than pristine WO₃ photocatalysts, respectively, depending on oxygen vacancies increased. In addition, it was confirmed that the bandgap process energy decreased from 2.95 eV to 2.64 and 2.45 eV after fluorine doping. From this result, it is considered that the direct vaper fluorination has an advantage for increasing the photocatalytic activities of WO₃ compared to that of the plasma fluorination.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1155-1158
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• 2004

Various inorganic alignment layers of nematic liquid crystal (NLC) molecules were investigated. Ar ion beam (IB) irradiation was utilized for alignment method and homogenous and homeotropic orientations with tilt angle were obtained on the suitable inorganic thin films. Proper doping materials were added to diamond-like carbon (DLC) films. In the case of homogeneous alignment, nitrogen doping affected the increase of pretilt angle, while the fluorine bonding in the DLC films was induced the tilted homeotropic alignment cause its extreme hydrophobic property. These results showed that ion beam irradiation method could be applied to the various alignment mode of NLC such as IPS, TN and MVA.

• Journal of the Optical Society of Korea
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• v.7 no.2
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• pp.89-96
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• 2003

A new method to control the free spectral range of a long period fiber grating is proposed and theoretically analyzed. As the refractive index decreases radially outward in the silica cladding due to graded doping of fluorine, waveguide dispersion in the cladding modes was modified to result in the effective indices change and subsequently the phase matching conditions for coupling with the core mode in a long period fiber grating. Enlargement of the free spectral range in a long period fiber grating was theoretically confirmed.

• Korean Journal of Materials Research
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• v.26 no.5
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• pp.258-265
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• 2016

Fluorine-doped tin oxide (FTO) nanoparticles have been successfully synthesized using ultrasonic spray pyrolysis. The morphologies, crystal structures, chemical bonding states, and electrochemical properties of the nanoparticles are investigated. The FTO nanoparticles show uniform morphology and size distribution in the range of 6-10 nm. The FTO nanoparticles exhibit excellent electrochemical performance with high discharge specific capacity and good cycling stability ($620mAhg^{-1}$ capacity retention up to 50 cycles), as well as excellent high-rate performance ($250mAhg^{-1}$ at $700mAg^{-1}$) compared to that of commercial $SnO_2$. The improved electrochemical performance can be explained by two main effects. First, the excellent cycling stability with high discharge capacity is attributed to the nano-sized FTO particles, which are related to the increased electrochemical active area between the electrode and electrolyte. Second, the superb high-rate performance and the excellent cycling stability are ascribed to the increased electrical conductivity, which results from the introduction of fluorine doping in $SnO_2$. This noble electrode structure can provide powerful potential anode materials for high-performance lithiumion batteries.