• Journal of the Korean institute of surface engineering
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• v.32 no.3
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• pp.244-248
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• 1999

Photoelectrodeposition of copper on semiconductive B-doped diamond films was investigated. There are cleasr morphology differences between photodeposited copper and electrodeposited copper. Photoelecrodeposition proceeded as uniform 2-dimensional growth. On the other hand electrodeposition proceeded as scarce random deposition. By applying this effect we have succeeded in forming a conductive pattern on semiconductive B-doped diamond with the aid of a photo-mask. And it was suggested that the surface reforming caused by photoelectrochemical process could be easily detected by the following metal (copper) deosition method, which is demonstrated as 'Diamond photographic phenomenon'.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.5
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• pp.1032-1037
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• 2003

Boron-doped CdS thin films were chemically deposited onto glass substrates. X-ray diffraction (XRD), photoluminescence (PL), and Raman techniques were used to evaluate the quality of B-doped CdS films. XRD results have confirmed that B-doped CdS films has a hexagonal structure with a preferential orientation of the (002) plane. The PL spectra for all samples consists of two prominent broad bands around 2.3 eV (green emission) and 1.6 eV (red emission) and the higher doping concentrations gradually decreased the green emission and red emission. Raman analysis has shown that undoped films have structure superior to those of B-doped CdS films. Boron doping into CdS films improved the optical transmittance and increased the optical band gap.

• ETRI Journal
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• v.23 no.4
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• pp.151-157
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• 2001

Spectroscopic and thermal analysis indicates that tellurite glasses doped with $B_2O_3$ and $GeO_2$ are promising candidate host materials for wide-band erbium doped fiber amplifier (EDFA) with a high 980 nm pump efficiency. In this study, we measured the thermal stabilities and the emission cross-sections for $Er^{3+}:^{4}I_{13/2}\;{\to}\;^{4}I_{15/2}$ transition in this tellurite glass system. We also determined the Judd-Ofelt parameters and calculated the radiative transition rates and the multiphonon relaxation rates in this glass system. The 15 mol% substitution of $B_2O_3$ for $TeO_2$ in the $Er^{3+}-doped\;75TeO_2-20ZnO-5K_2O$ glass raised the multiphonon relaxation rate for $^4I_{11/2}\;{\to}\;^4I_{13/2}$ transition from 4960 $s^{-1}$ to 24700 $s^{-1}$, but shortened the lifetime of the $^4I_{13/2}$ level by 14 % and reduced the emission cross-section for the $^4I_{13/2}\;{\to}\;^4I_{15/2}$ transition by 11%. The 15 mol% $GeO_2$ substitution in the same glass system also reduced the emission cross-section but increased the lifetime by 7%. However, the multiphonon relaxation rate for $^4I_{11/2}{\to}^4I_{13/2}$ transition was raised merely by 1000 $s^{-1}$. Therefore, a mixed substitution of $B_2O_3$ and $GeO_2$ for $TeO_2$ was concluded to be suitable for the 980 nm pump efficiency and the fluorescence efficiency of $^4I_{13/2}{\to}^4I_{15/2}$ transition in $Er^{3+}-doped$ tellurite glasses.

• Journal of the Korean Magnetics Society
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• v.8 no.6
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• pp.346-349
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• 1998

In order to reduce to the defect density in poly-Si/SiO$_2$ thin films, where poly-Si is either undoped or doped by BF$_2$ implantation, the poly-Si/SiO$_2$ samples have been hydrogenated by rf plasmas of low temperature. Before hydrogenation, both $P_b$ centers and E centers were observed in the poly-Si(undoped)/SiO$_2$ and in the poly-Si(doped)/SiO$_2$. After 30 min hydrogenation, the $P_b$ center was reduced by 80 % doped sample and by 76 % in the undoped sample and the E center was not observed. After 90min hydrogenation, however, increases of the $P_b$ centers and regenerations of the E center were observed in the undoped sample as well as in the doped one. Compared with the undoped sample, the increase of $P_b$ center in the doped one was more dominant.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.11
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• pp.1666-1671
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• 2022

The structure of a high-power gain-flattened long wavelength band (L-band) optical amplifier was optimized, which was implemented for 64-channel wavelength division multiplexed optical signals with a channel spacing of 50 GHz. The output characteristics of this L-band amplifier were measured and analyzed. The amplifier of the optimized two-stage amplification configuration had a flattened gain of 20 dB within 1 dB deviation between 1570 and 1600 nm for -2 dBm input power condition. The noise figure under this condition was minimized to within 6 dB in the amplification bandwidth. The gain flattening was realized by considering only the characteristics of gain medium in the amplifier without using additional optical or electrical devices. The proposed amplifier consisted of two stages of amplification stages, each of which was based on the erbium-doped fiber amplifier (EDFA) structure. The erbium-doped fiber length and pumping structures in each stage of the amplifier were optimized through experiments.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.406-409
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• 2012

Recently, enormous research efforts have been focused on the development of non-precious catalysts to replace Pt for electrocatalytic oxygen reduction reaction (ORR), and to reduce the cost of proton exchange membrane fuel cells (PEMFCs). In recent years, heteroatom (N, B, and P) doped carbon nanostructures have been received enormous importance as a non-precious electrode materials for oxygen reduction. Doping of foreign atom into carbon is able to modify electronic properties of carbon materials. In this study, nitrogen and boron doped carbon nanostructures were synthesized by using a facile and cost-effective thermal annealing route and prepared nanostructures were used as a non-precious electrocatalysts for the ORR in alkaline electrolyte. The nitrogen doped carbon nanocapsules (NCNCs) exhibited higher activity than that of a commercial Pt/C catalyst, excellent stability and resistance to methanol oxidation. The boron-doped carbon nanostructure (BC) prepared at $900^{\circ}C$ showed higher ORR activity than BCs prepared lower temperature (800, $700^{\circ}C$). The heteroatom doped carbon nanomaterials could be promising candidates as a metal-free catalysts for ORR in the PEMFCs.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.2
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• pp.75-78
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• 2009

Si-doped GaAs single crystals were grown by vertical gradient freeze using PBN crucibles. The amount of oxide layer $B_{2}O_{3}$ in PBN crucible was changed($0{\sim}0.2wt%$) and measured the concentration of carriers. The segregation coefficients of Si in GaAs melt decreased rapidly from initial 0.1 to 0.01 as the amount of $B_{2}O_{3}$ increases. At the same time, concentration of carriers was shown to decrease. It is likely that the reaction between dopant Si and $B_{2}O_{3}$ in GaAs melt results in the reduction of Si dopants(donor) while increase in the amount of boron(acceptor). The thin layer of $B_{2}O_{3}$ glass in PBN crucible was proved to be a better way to reduce defect formation rather than the total amount of $B_{2}O_{3}$.

• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.29-33
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• 2010

In this study, boron, carbon, nitrogen and fluorine co-doped $TiO_{2}$ photocatalysts using tetraethylammonium tetrafluoroborate (TEATFB) have been prepared by different heat treatment temperatures to decrease the band gap. To explore the visible light photocatalytic activity of the novel low‐zband gap $TiO_{2}$ photocatalyst, the removal of two dyes was investigated, namely, acridine orange and rhodamine B. XRD patterns demonstrate that the samples calcined at temperatures up to $800^{\circ}C$ clearly show anatase peaks. The XPS results show that all the doped samples contain N, C, B and F elements and the doped $TiO_{2}$ shows the shift in the band gap transition down to 2.98 eV as UV-DRS results. In these UV-Vis results, photocatalytic activity of the doped $TiO_{2}$ is 1.61 times better than undoped $TiO_{2}$. Specially, excellent photoactivity results were obtained in the case of samples treated at $700^{\circ}C$.

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.11a
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• pp.70-70
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• 1999

• 한국초전도학회:학술대회논문집
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• 2009.07a
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• pp.91-91
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• 2009