• 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.

• Journal of Magnetics
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• v.20 no.2
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• pp.97-102
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• 2015

The waste of sintered Nd-Fe-B magnets was recycled using the method of dopingPrNd nanoparticles. The effect of PrNd nanoparticle doping on the magnetic properties of the regenerated magnets has been studied. As the content of the PrNd nanoparticles increases, the coercivity increases monotonically, whereas both the remanence and the maximum energy products reach the maximum values for 4 wt% PrNd doping. Microstructural observation reveals that the appropriate addition of PrNd nanoparticles improves the magnetic properties and refines the grain. Domain investigation shows that the self-pinning effect of the rare earth (Re)-rich phase is enhanced by PrNd nano-particle doping. Compared to the magnet with 4 wt% PrNd alloy prepared using the dual-alloy method, the regenerated magnet doped with the same number of PrNd nanoparticles exhibits better magnetic properties and a more homogeneous microstructure. Therefore, it is concluded that PrNd nanoparticle doping is an efficient method for recycling the leftover scraps of Nd-Fe-B magnets.

• Journal of Magnetics
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• v.16 no.1
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• pp.15-18
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• 2011

We have studied the $TiO_2$ doping effects on the flux pinning behavior of an $MgB_2$ superconductor synthesized by the in-situ solid-state reaction. From the field-cooled and zero-field-cooled temperature dependences of magnetization, the reversible-irreversible transition of $TiO_2$-doped $MgB_2$ was determined in the H-T diagram (the temperature dependence of upper critical magnetic field and irreversibility line). For comparison, the similar measurements are also obtained from SiC-doped $MgB_2$. The critical current density was estimated from the width of hysteresis loops in the framework of Bean's model at different temperatures. The obtained results manifest that nano-scale $TiO_2$ inclusions served as effective pinning centers and lead to the enhanced upper critical field and critical current density. It was concluded that the grain boundary pinning mechanism was realized in a $TiO_2$-doped $MgB_2$ superconductor.

• Progress in Superconductivity
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• v.10 no.1
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• pp.17-22
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• 2008

We have examined the effect of ball-milling on the superconducting properties of $MgB_2$ doped with C. The ball-milling of pre-reacted $MgB_2$ powder was carried out in dry or wet state using C or diethylenetriamine ($C_{4}H_{13}N_3$) as additives. The diethylenetriamine, whose chemical formula contains no oxygen, was chosen to avoid an excess oxidation during doping. The superconducting transition temperature (Tc) of the ball-milled or doped $MgB_2$ powders was only slightly smaller than that of undoped $MgB_2$. The critical current density (Jc) of the highly ball-milled $MgB_2$ was higher than that of C-doped $MgB_2$. The addition of diethylenetriamine was detrimental to Jc, although Tc was almost unchanged.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.915-917
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• 1999

We investigated the effects of doping elements on the Bi system superconductor. The doping elements can be classified into two groups depending on their supeconducting characteristics in the Bi-Sr-Ca-Cu-O structure. The first group of doping elements(P and K) have a tendency to decompose the superconducting phase and reduce the optimal sintering temperature. The second group of doping elements(B, Si, Sn and Ba) almost uneffected the superconductivity of the 2223 and 2212 phase.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.63-63
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• 2009

In this work, we demonstrate 800V 4H-SiC power DMOSFETs with several structural alterations to observe static DC characteristics, such as a threshold voltage ($V_{TH}$) and a figure of merit ($V_B^2/R_{SP,ON}$). To optimize the static DC characteristics, we consider four design parameters; (a) the doping concentration ($N_{CSL}$) of current spreading layer (CSL) beneath the p-base region, (b) the thickness of p-base ($t_{BASE}$), (c) the doping concentration ($N_J$) and width ($W_J$) of a JFET region, (d) the doping concentration ($N_{EPI}$) and thickness ($t_{EPI}$) of epi-layer. Design parameters are optimized using 2D numerical simulations and the 4H-SiC DMOSFET structure results in high figure of merit ($V_B^2/R_{SP,ON}$>~$340MW/cm^2$) for a power MOSFET in $V_B{\sim}1200V$ range.

• 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.22 no.8
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• pp.637-640
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• 2009

In this work, we demonstrate 800 V 4H-SiC power DMOSFETs with several structural alterations to obtain a low threshold voltage ($V_{TH}$) and a high figure of merit ($V_B\;^2/R_{SP,ON}$), To optimize the device performance, we consider four design parameters; (a) the doping concentration ($N_{CSL}$) of current spreading layer (CSL) beneath the p-base region, (b) the thickness of p-base ($t_{BASE}$), (c) the doping concentration ($N_J$) and width ($W_J$) of a JFET region, (d) the doping concentration ($N_{EPI}$) and thickness ($t_{EPI}$) of epi-layer. These parameters are optimized using 2D numerical simulation and the 4H-SiC DMOSFET structure results in a threshold voltage ($V_{TH}$) below $^{\sim}$3.8 V, and high figure of merit ($V_B\;^2/R_{SP,ON}$>$^{\sim}$200 $MW/cm^2$) for a power MOSFET in $V_B\;^{\sim}$800 V range.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.752-755
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• 2006

Reverse annealing was observed in $P^+/B^+$ ion shower doped poly-Si upon activation annealing. Phosphorous or boron was implanted by ion shower doping using a source gas mixture of $PH_3/H_2$ or $B_2H_6/H_2$. Activation annealing was conducted using a tube furnace in the temperature ranges from $350^{\circ}C$ to $650^{\circ}C$. Hall measurement revealed that reverse annealing begins at different annealing temperatures for poly-Si implanted with P and B, respectively. It was observed that reverse annealing starts at $550^{\circ}C$$ in $P^+$ ion shower doped poly-Si, while at $350^{\circ}C$ in the case of B-doping.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.6
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• pp.248-252
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• 2008

To get a fine $LiFePO_4$ powder with high electrical conductivity, the influences of doping of aliovalent elements(Cr+B and Cr+Al) on electrical conductivity and of heat treatment conditions on particle size of the doped powders were studied. Two kinds of the doped powders $LiFe_{0.965}Cr_{0.03}B_{0.005}PO_4$ and $LiFe_{0.065}Cr_{0.03}Al_{0.005}PO_4$ were synthesized using mechanochemical milling and subsequent heat treatment at $675{\sim}750^{\circ}C$ for $5{\sim}10\;h$. The doping enhanced grain growth and electrical conductivity. The electrical conductivity at $30^{\circ}C$ was $1{\times}10^{-8}S/cm$ in the doped with Cr and Al, and $5{\times}10^{-10}S/cm$ in the undoped one.