• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1067-1072
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• 2014

In this study, we report a new approach for $Mn_3O_4$-graphene nanocomposite by ex situ method. This nanocomposite shows two-dimensional aggregation of nanoparticle, and doping effect by decorated manganese oxide ($Mn_3O_4$), as well. The graphene film was made through micromechanical cleavage of graphite on the $SiO_2/Si$ wafer. Manganese oxide ($Mn_3O_4$) nanoparticle with uniform cubic shape and size (about $5.47{\pm}0.61$ nm sized) was synthesized through the thermal decomposition of manganese(II) acetate, in the presence of oleic acid and oleylamine. The nanocomposite was obtained by self-assembly of nanoparticles on graphene film, using hydrophobic interaction. After heat treatment, the decorated nanoparticles have island structure, with one-layer thickness by two-dimensional aggregations of particles, to minimize the surface potential of each particle. The doping effect of $Mn_3O_4$ nanoparticle was investigated with Raman spectra. Given the upshift in positions of G and 2D in raman peaks, we suggest that $Mn_3O_4$ nanoparticles induce p-doping of graphene film.

• Journal of the Korean Institute of Gas
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• v.15 no.3
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• pp.74-78
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• 2011

$BF_3$ gas has been used for semiconductor manufacturing process and applied in plasma etching, chemical vapor deposition, chamber cleaning processes etc,. $BF_3$ provides Boron and acts as a p-type doping in electrode in semiconductor. In this study, we investigate thermaldecomposition of alkali-boron complexes and suggest a simple way to produce $BF_3$ from $NaBF_4$ and $KBF_4$.

• Bulletin of the Korean Chemical Society
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• v.27 no.11
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• pp.1844-1850
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• 2006

Two types of catalyst samples were prepared, one sulfated zirconia and the other silica doped sulfated zirconia. The acidity tests indicate that sulfated zirconia doped with silica has higher concentration and strength of acidic catalyst sites than undoped sulfated zirconia. The acidic surface sites have been characterized using FTIR, NMR, pyridine adsorption, TPD, XRD and nitrogen adsorption. Doping with silica increased the concentration of surface Lewis and Brfnsted acid sites and resulted in generation of proximate acid sites.The activity test indicates that doping sulfated zirconia with silica increases both the acidity and catalytic activity for liquid phase dehydration of methanol at 413-453 K. Methanol is sequentially dehydrated to dimethyl ether and ethylene over both catalysts. Significant amounts of propylene are also formed over the silica-doped catalyst, but not over the undoped catalyst.

• Carbon letters
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• v.9 no.2
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• pp.131-136
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• 2008

In order to investigate the effect of doping C, N, B and F elements on $TiO_2$ for reducing the band gap, the heat treatment of $TiO_2$ was carried out with tetraethylammonium tetrafluoroborate. Through XRD and XPS analysis, the C, N, B and F doped anatase $TiO_2$ was confirmed. According to the increase of temperature during treatment, the particle size was increased due to aggregation of $TiO_2$ with elements (B, C, N and F). To investigate the capacity of photocatalyst for degradation of dye under solar light, the degradation of acridine orange and methylene blue was conducted. The degradation of dyes was carried out successfully under solar light indicating the effect of doping elements (B, C, N and F) on $TiO_2$ for reducing the band gap effectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.12
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• pp.1301-1307
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• 2004

Reduced pressure chemical vapor deposition(RPCYD) technology has been investigated for the growth of SiGe epitaxial films with two dimensional in-situ doped boron impurities. The two dimensional $\delta$-doped impurities can supply high mobility carriers into the channel of SiGe heterostructure MOSFETs(HMOS). Process parameters including substrate temperature, flow rate of dopant gas, and structure of epitaxial layers presented significant influence on the shape of two dimensional dopant distribution. Weak bonds of germanium hydrides could promote high incorporation efficiency of boron atoms on film surface. Meanwhile the negligible diffusion coefficient in SiGe prohibits the dispersion of boron atoms: that is, very sharp, well defined two-dimensional doping could be obtained within a few atomic layers. Peak concentration and full-width-at-half-maximum of boron profiles in SiGe could be achieved in the range of 10$^{18}$ -10$^{20}$ cm$^{-3}$ and below 5 nm, respectively. These experimental results suggest that the present method is particularly suitable for HMOS devices requiring a high-precision channel for superior performance in terms of operation speed and noise levels to the present conventional CMOS technology.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.15-15
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• 2011

Atom-thick graphene membrane and nano-sized graphene objects (NGOs) hold substantial potential for applications in future molecular-scale integrated electronics, transparent conducting membranes, nanocomposites, etc. To realize this potential, chemical properties of graphene need to be understood and diagnostic methods for various NGOs are also required. To meet these needs, chemical properties of graphene and optical diagnostics of graphene nanoribbons (GNRs) have been explored by Raman spectroscopy, AFM and STM scanning probes. The first part of the talk will illustrate the role of underlying silicon dioxide substrates and ambient gases in the ubiquitous hole doping of graphene. An STM study reveals that thermal annealing generates out-of-plane deformation of nanometer-scale wavelength and distortion in $sp^2$ bonding on an atomic scale. Graphene deformed by annealing is found to be chemically active enough to bind molecular oxygen, which leads to a strong hole-doping. The talk will also introduce Raman spectroscopy studies of GNRs which are known to have nonzero electronic bandgap due to confinement effect. GNRs of width ranging from 15 nm to 100 nm have been prepared by e-beam lithographic patterning of mechanically exfoliated graphene followed by oxygen plasma etching. Raman spectra of narrow GNRs can be characterized by upshifted G band and strong disorder-related D band originating from scattering at ribbon edges. Detailed analysis of the G, D, and 2D bands of GNRs proves that Raman spectroscopy is still a reliable tool in characterizing GNRs despite their nanometer width.

• Journal of Ceramic Processing Research
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• v.20 no.3
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• pp.222-230
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• 2019

Microwave hydrothermal-assisted sol-gel method was employed to synthesize the Fe doped TiO2 photocatalyst. The morphological analysis suggests anatase phase nanoparticles of ~20 nm with an SBET area of 283.99 ㎡/g. The doping of Fe ions in TiO2 created oxygen vacancies and Ti3+ species as revealed through the XPS analysis. The reduction of the band gap (3.1 to 2.8 eV) is occurred by doping effect. The as-prepared photocatalyst was applied for removal of NOx under solar light irradiation. The doping of Fe in TiO2 facilitates 75 % of NOx oxidation efficiency which is more than two-fold enhancement than the TiO2 photocatalyst. The possible reason of enhancement is associated with high surface area, oxygen vacancy, and reduction of the band gap. Also, the low production of toxic intermediates, NO2 gas, is further confirmed by Combustion Ion Chromatography. The mechanism related NOx oxidation by the doped photocatalyst is explained in this study.

• Journal of the Korean Chemical Society
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• v.45 no.3
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• pp.282-285
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• 2001

• Bulletin of the Korean Chemical Society
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• v.10 no.5
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• pp.474-475
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• 1989

• Korean Journal of Materials Research
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• v.24 no.3
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• pp.140-144
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• 2014

The contact mechanism of devices is usually researched at electrode contacts. However, the contact between a dielectric and channel at the MOS structure is more important. The graphene was used as a channel material, and the thin film transistor with MOS structure was prepared to observe the contact mechanism. The graphene was obtained on Cu foil by the thermal decomposition method with $H_2$ and $CH_4$ mixed gases at an ambient annealing temperature of $1000^{\circ}C$ during the deposition for 30 min, and was then transferred onto a $SiO_2/Si$ substrate. The graphene was doped in a nitrogen acidic solution. The chemical properties of graphene were investigated to research the effect of nitric atoms doping. The sheet resistance of graphene decreased after nitrogen acidic doping, and the sheet resistance decreased with an increase in the doping times because of the increment of negative charge carriers. The nitric-atom-doped graphene showed the Ohmic contact at the curve of the drain current and drain voltage, in spite of the Schottky contact of grapnene without doping.