• Bulletin of the Korean Chemical Society
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• 제33권1호
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• pp.199-203
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• 2012

A modified sol-gel method and $N_2$-plasma treatment were used to prepare bulk and surface doped N-$TiO_2$, respectively. XRD, TEM, UV-vis spectroscopy, $N_2$ adsorption, Elemental Analyzer, Photoluminescence, and XP spectra were used to characterize the prepared $TiO_2$ samples. The N doping did not change the phase composition and particle sizes of $TiO_2$ samples, but increased the visible light absorption. The photocatalytic activities were tested in the degradation of an aqueous solution of a reactive dyestuff, methylene blue, under visible light. The photocatalytic activity of surface doped N-$TiO_2$ prepared by $N_2$-plasma was much higher than that of bulk doped N-$TiO_2$ prepared by sol-gel method. The possible mechanism for the photocatalysis was proposed.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권2호
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• pp.191-197
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• 2016

In this paper, we investigated the hotcarrier injection (HCI) mechanism, one of the most important reliability issues, in 10 nm node Input/Output (I/O) bulk FinFET. The FinFET has much intensive HCI damage in Fin-bottom region, while the HCI damage for planar device has relatively uniform behavior. The local damage behavior in the FinFET is due to the geometrical characteristics. Also, the HCI is significantly affected by doping profile, which could change the worst HCI bias condition. This work suggested comprehensive understanding of HCI mechanisms and the guideline of doping profile in 10 nm node I/O bulk FinFET.

• 대한전자공학회논문지SD
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• 제48권10호
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• pp.62-66
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• 2011

본 연구에서는 측정된 S-파라미터를 사용하여 드레인-소스 전압 Vds에 무관한 게이트-소스 overlap 캐패시턴스를 추출하고, 이를 바탕으로 deep-submicron MOSFET의 Vds 종속 게이트-벌크 캐패시턴스 곡선을 추출하는 RF 방법이 새롭게 개발 되었다. 추출된 캐패시턴스 값들을 사용한 등가회로 모델과 측정된 데이터가 잘 일치하는 것을 관찰함으로써 추출방법의 정확도가 검증되었다. 추출된 데이터로부터 overlap과 depletion 길이의 Vds 종속 곡선이 얻어졌으며, 이를 통해 drain 영역의 채널 도핑 분포를 실험적으로 측정하였다.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2008년도 High Temperature Superconductivity Vol.XVIII
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• pp.88-88
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• 2008

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.1054-1056
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• 2002

High temperature Kermal diffusion from $POCl_3$ source usually used for conventional process through put of a cell manufacturing line and potentially reduce cell efficiency through bulk like time degradation. To fabricate high efficiency solar cells with minimal thermal processing, spin-on-doping(SOD) technique can be employed to emitter diffusion of a silicon solar cell. A technique is presented to emitter doping of a mono-crystalline solar cell using spin-on doping (SOD). Moreover it is shown that the sheet resistance variation with RTA temperature and time fer mono-crystalline and multi-crystalline silicon samples. This novel SOD technique was successfully used to produces 11.3% efficiency l04mm by 104mm size mono-crystalline silicon solar cells.

• 한국초전도ㆍ저온공학회논문지
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• 제16권2호
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• pp.36-41
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• 2014

Temperature dependence of magnetic moment (m-T) and the magnetization (M-H) at 5 K and 20 K of the in situ processed $MgB_2$ bulk pellets with/without carbon (C) doping were examined. The superconducting critical temperature ($T_c$), the superconducting transition width (${\delta}T$) and the critical current density ($J_c$) were estimated for ten test samples taken from the $MgB_2$ bulk pellets. The reliable m-T characteristics associated with the uniform $MgB_2$ formation were obtained for both $MgB_2$ pellets. The $T_cs$ and ${\delta}Ts$ of all test samples of the undoped $MgB_2$ were the same each other as 37.5 K and 1.5 K, respectively. The $T_cs$ and ${\delta}Ts$ of the C-doped $MgB_2$ were 36.5 K and 2.5 K, respectively. Unlike the m-T characteristics, there existed the difference among the M-H curves of the test samples, which might be caused by the microstructure variation. In spite of the slight $T_c$ decrease, the C doping was effective in enhancing the $J_c$ at 5 K.

• 한국전기전자재료학회논문지
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• 제35권4호
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• pp.407-411
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• 2022

Bulk-sized PbTiO₃ (PT), which is widely known as a high-performance ferroelectric oxide but cannot be fabricated into a monolithic ceramic due to its high c/a ratio, was successfully prepared with a high tetragonality by partially substituting Ni ions for Pb ions using a solid-state reaction method. We found that Ni-doped PT was well-fabricated as a bulk monolith with a significant c/a ratio of ~1.06. X-ray diffraction on as-sintered and crushed samples revealed that NiTiO₃ secondary phase was present at the doping level of more than 2 at.%. Scanning electron microscopic study showed that NiTiO₃ secondary phase grew on the surface of PT specimens regardless of the doping level possibly due to the evaporation of Pb during sintering. We demonstrated that an unconventional introduction of Ni ions into A-site plays a key role on the fabrication of bulk PT, though how Ni ion functions should be studied further. We expect that this study contributes to a further development of displacive ferroelectric oxides with a high c/a ratio.

• Bulletin of the Korean Chemical Society
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• 제35권3호
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• pp.895-898
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• 2014

The wavelength dependence of the photoacoustic signal for n-type GaAs semiconductors in the region of the band-gap energies was investigated. The significant changes in the phase and amplitude of the photoacoustic signal near the band-gap absorption wavelengths were observed to occur when the Si-doping densities in GaAs were varied. Particularly, the first derivatives of the photoacoustic phase vs. wavelength graphs were evaluated and fitted with single Gaussian functions. The peak centers and the widths of the Gaussian curves clearly showed linear relationships with the log values of the Si-doping densities in n-type GaAs semiconductors. It is proposed that the wavelength-dependent PA spectroscopy can be used as a simple and nondestructive method for measuring the doping densities in bulk semiconductors.

• 대한전자공학회논문지SD
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• 제43권11호
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• pp.1-7
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• 2006

이상적인(ideal) 이중-게이트(double-gate) 벌크(bulk) FinFET의 3차원(3-D) 시뮬레이션을 수행하여 전기적 특성들을 분석하였다. 3차원 시뮬레이터를 이용하여, 게이트 길이($L_g$)와 높이($H_g$), 핀 바디(fin body)의 도핑농도($N_b$)를 변화시키면서 소스/드레인 접합 깊이($X_{jSDE}$)에 따른 문턱전압($V_{th}$), 문턱전압 변화량(${\Delta}V_{th}$), DIBL(drain induced barrier lowering), SS(subthreshold swing)의 특성들을 살펴보았다. 게이트 높이가 35 nm인 소자에서 소스/드레인 접합 깊이(25 nm, 35 nm, 45 nm) 변화에 따라, 각각의 문턱전압을 기준으로 게이트 높이가 $30nm{\sim}45nm$로 변화 될 때, 문턱전압변화량은 20 mV 이하로 그 변화량이 매우 적음을 알 수 있었다. 낮은 핀 바디 도핑농도($1{\times}10^{16}cm^{-3}{\sim}1{\times}10^{17}cm^{-3}$)에서, 소스/드레인 접합 깊이가 게이트전극보다 깊어질수록 DIBL과 SS는 급격히 나빠지는 것을 볼 수 있었고. 이러한 특성저하들은 $H_g$ 아래의 ${\sim}10nm$ 위치에 국소(local) 도핑을 함으로써 개선시킬 수 있었다. 또한 local 도핑으로 소스/드레인 접합 깊이가 얕아질수록 문턱전압이 떨어지는 것을 개선시킬 수 있었다.

• Progress in Superconductivity
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• 제11권2호
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• pp.87-91
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• 2010

We fabricated the polyacrylic acid (PAA)-doped $MgB_2$ bulks and characterized their lattice parameters, actual C substitutions, microstructures, and critical properties. The boron (B) powder was mixed with PAA using N,N-dimethylformamide as solvent and then the solution was dried out at $200^{\circ}C$ and crushed. The C treated B powder and magnesium powder were mixed and compacted by uniaxial pressing at 500 MPa, followed by sintering at $900^{\circ}C$ for 1 h in high purity Ar atmosphere. We observed that the PAA doping increased the MgO amount but decreased the grain size, a-axis lattice constant, and critical temperature ($T_c$), which is indicative of the C substitution for B sites in $MgB_2$. In addition, the critical current density ($J_c$) at high magnetic field was significantly improved with increasing PAA addition: at 5 K and 6.6 T, the $J_c$ of 7 wt% PAA-doped sample was $6.39\;{\times}\;10^3\;A/cm^2$ which was approximately 6-fold higher than that of the pure sample ($1.04\;{\times}\;10^3\;A/cm^2$). This improvement was probably due to the C substitution and the refinement of grain size by PAA doping, suggesting that PAA is an effective dopant in improving $J_c$(B) performance of $MgB_2$.