• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04a
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• pp.65-66
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• 2008

The realization and origin of p-type ZnO are main issue for photoelectronic devices based on ZnO material. N-doped and nominally undoped p-type ZnO films were achieved on silicon (100) and homo-buffer layers by RF magnetron sputtering and post in-situ annealing. The undoped film shows high hole mobility of 1201 $cm^2V^{-1}s^{-1}$ and low resistivity of $0.0454\Omega{\cdot}cm$ with hole concentration of $1.145\times10^{17}cm^{-3}$. The photoluminescence(PL) spectra show the emissions related to FE, DAP and defects of $V_{Zn}$, $V_O$, $Zn_O$, $O_i$ and $O_{Zn}$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.4
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• pp.809-815
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• 2000

The box capacitor structure with HSG-Si described here reliably achieves a cell capacitance of 28fF with a cell area of a $0.4820\mum^2$ for 128Mbit DRAM. An HSG-Si formation technology with seeding method, which employs Si2H6 molecule irradiation and annealing, was applied for realizing 64Mbit and larger DRAMS. By using this technique, grain size controlled HSG-Si can be fabricated on in-situ phosphorous doped amorphous silicon electrodes. The HSG-Si fabrication technology achieves twice the storage capacitance with high reliability for the stacked capacitors.The box capacitor structure with HSG-Si described here reliably achieves a cell capacitance of 28fF with a cell area of a $0.4820\mum^2$ for 128Mbit DRAM. An HSG-Si formation technology with seeding method, which employs Si2H6 molecule irradiation and annealing, was applied for realizing 64Mbit and larger DRAMS. By using this technique, grain size controlled HSG-Si can be fabricated on in-situ phosphorous doped amorphous silicon electrodes. The HSG-Si fabrication technology achieves twice the storage capacitance with high reliability for the stacked capacitors.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.172-172
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• 2010

$MgB_2$ doped with $TiO_2$ was prepared by the in-situ solid state reaction to study the effects of $TiO_2$ dopant on the flux pinning behavior of $MgB_2$ superconductor. From the field-cooled and the zero-field-cooled temperature dependences of magnetization, the realms of vortex-glass and vortex-liquid states of $TiO_2$-doped $MgB_2$ were determined in the H-T diagram (the temperature dependence of upper critical magnetic field and irreversibility line). The critical current density was estimated from the width of hysteresis loops in the framework of Beam's model at different temperatures. The results indicate that nano-scale $TiO_2$ inclusions play a role of the effective pinning centers and lead to the enhanced upper critical field and critical current density. It is suggested that the grain-boundary pinning mechanism is realized in $TiO_2$-doped $MgB_2$ superconductor.

• 한국초전도학회:학술대회논문집
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• 2009.07a
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• pp.92-92
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• 2009

• Transactions on Electrical and Electronic Materials
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• v.12 no.5
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• pp.200-203
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• 2011

In this research, nitrogen (N)-doped zinc oxide (ZnO) thin films have been grown on a sapphire substrate by dielectric barrier discharge (DBD) in pulsed laser deposition (PLD). DBD has been used as an effective way for massive in-situ generation of N-plasma under conventional PLD process conditions. Low-temperature photoluminescence spectra of N-doped ZnO thin films provided near-band-edge emission after a thermal annealing process. The emission peak was resolved by Gaussian fitting and showed a dominant acceptor-bound excitation peak ($A^{\circ}X$) that indicated acceptor doping of ZnO with N. The acceptor binding energy of the N acceptor was estimated to be approximately 145 MeV based on the results of temperature-dependent photoluminescence (PL) measurements.

• Progress in Superconductivity and Cryogenics
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• v.16 no.1
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• pp.9-13
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• 2014

Effects of neutron irradiation on the superconducting properties of the undoped $MgB_2$ and the carbon(C)-doped $MgB_2$ bulk superconductors, prepared by an in situ reaction process using Mg and B powder, were investigated. The prepared $MgB_2$ samples were neutron-irradiated at the neutron fluence of $10^{16}-10^{18}n/cm^2$ in a Hanaro nuclear reactor of KAERI involving both fast and thermal neutron. The magnetic moment-temperature (M-T) and magnetization-magnetic field (M-H) curves before/after irradiation were obtained using magnetic property measurement system (MPMS). The superconducting critical temperature ($T_c$) and transition width were estimated from the M-T curves and critical current density ($J_c$) was estimated from the M-H curves using a Bean's critical model. The $T_cs$ of the undoped $MgB_2$ and C-doped $MgB_2$ before irradiation were 36.9-37.0 K and 36.6-36.8 K, respectively. The $T_cs$ decreased to 33.2 K and 31.6 K, respectively after irradiation at neutron fluence of $7.16{\times}10^{17}n/cm^2$, and decreased to 22.6 K and 24.0 K, respectively, at $3.13{\times}10^{18}n/cm^2$. The $J_c$ cross-over was observed at the high magnetic field of 5.2 T for the undoped $MgB_2$ irradiated at $7.16{\times}10^{17}n/cm^2$. The $T_c$ and $J_c$ variation after the neutron irradiation at various neutron fluences were explained in terms of the defect formation in the superconducting matrix by neutron irradiation.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.38.1-38.1
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• 2010

The trend to thinner crystalline silicon solar wafers in production of solar cells investigates re-evolution of back surface field (BSF) formation. We have studied mechanisms of back contact formation in Al evaporation and screen printed Al paste for Si solar cells by TEM analysis. We observed that Si diffuse into Al during heat up. The Si diffusion process made vacancies in Si wafer. The Al began to seep into the Si wafer (Al spike). During heat down, the Al spike were shrink which causes the doped region (BSF).

• 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.6
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• pp.372-375
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• 2017

ZnO thin films were deposited by RF magnetron sputtering and then diffused by using an As source in the ampouletube. Also, the ZnO p-n homojunction was made by using As-doped ZnO thin films, and its properties were analyzed. After the As doping, the surface roughness increased, the crystal quality deteriorated, and the full width at half maximum was increased. The As-doped ZnO thin films showed typical p-type properties, and their resistivity was as low as $2.19{\times}10^{-3}{\Omega}cm$, probably because of the in-diffusion from an external As source and out-diffusion from the GaAs substrate. Also, the ZnO p-n junction displayed the typical rectification properties of a p-n junction. Therefore, the As diffusion method is effective for obtaining ZnO films with p-type properties.

• Journal of the Korean Ceramic Society
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• v.45 no.12
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• pp.788-795
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• 2008

An electrolyte supported SOFC cell was tested at $800^{\circ}C$ in air for 3600 h with an applied current density of $200\;mA/cm^2$ to examine possible cathode degradation issues. A scandium- stabilized zirconia (ScSZ) with additional manganese doping (ScSZ: Mn) was used as electrolyte. A strontium and copper-doped lanthanum ferrite (LaSrCuFe) and platinum were used as cathode and quasi-anode material, respectively. The DC resistance was logged over the complete testing period. Additionally, impedance spectroscopy was used from time to time to track changes of the cell in-situ. Post-test analysis of the cell using methods like scanning electron microscopy imaging and other electrochemical testing methods allow the identification of different degradation sources. The results indicate a promising combination of electrolyte and cathode material in terms of chemical compatibility and electrical performance.