• 한국세라믹학회지
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• 제53권2호
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• pp.145-149
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• 2016

$(Bi_{1/2}Na_{1/2})_{0.94}Ba_{0.06}(Ti_{1-x}Nb_x)O_3$ (BNBTxNb) ceramics were investigated in terms of the crystal structure as well as the ferroelectric, dielectric, and piezoelectric properties. While little change was observed in the microstructure except for a slight decrease in the average grain size, a significant change was noticed in the temperature dependence of dielectric and piezoelectric properties. It was shown that the property changes are closely related to the downward shift in the position of the ferroelectric-to-relaxor transition temperature with increasing amount of Nb doping. A special emphasis is put on the fact that Nb doping is so effective at decreasing the ferroelectric-to-relaxor transition temperature that even at no more than 2 at.% Nb addition, the transition temperature was already brought down slightly below room temperature, resulting in the birth of a large strain at 0.46 %, equivalent to $S_{max}/E_{max}=767pm/V$.

• 한국재료학회지
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• 제16권11호
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• pp.705-709
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• 2006

Nb was doped to Pb-free $(Bi_{0.5}Na_{0.5})TiO_3$ (BNT) by a solid state mixing process to form $(Bi_{0.5}Na_{0.5})Ti_{1-x}Nb_xO_3\;(x=0{\sim}0.05)$ (BNTNb) and its doping effects on ferroelectric and piezoelctric properties of BNT were investigated. The BNTNb solid solutions were formed up to x=0.01 with no apparent second phases while grain sizes decreased. As x increased, coercive field ($E_c$) and mechanical quality factor ($Q_m$) decreased but piezoelectric constant ($d_{33}$) increased, which indicates Nb acts as a donor for BNT.

• Nuclear Engineering and Technology
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• 제53권12호
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• pp.4106-4113
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• 2021

Rare earth doped barium tellurite glasses were synthesised and explored for their radiation shielding applications. All the samples showed good thermal stability with values varying between 101 ℃ and 135 ℃ based on dopants. Structural properties showed the dominance of matrix elements compared to rare earth dopants in forming the bridging and non-bridging atoms in the network. Bandgap values varied between 3.30 and 4.05 eV which was found to be monotonic with respective rare earth dopants indicating their modification effect in the network. Various radiation shielding parameters like linear attenuation coefficient, mean free path and half value layer were calculated and each showed the effect of doping. For all samples, LAC values decreased with increase in energy and is attributed to photoelectric mechanism. Thulium doped glasses showed the highest value of 1.18 cm^-1 at 0.245 MeV for 2 mol.% doping, which decreased in the order of erbium, holmium and the base barium tellurite glass, while half value layer and mean free paths showed an opposite trend with least value for 2 mol.% thulium indicating that thulium doped samples are better attenuators compared to undoped and other rare earth doped samples. Studies indicate an increased level of thulium doping in barium tellurite glasses can lead to efficient shielding materials for high energy radiation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 반도체재료
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• pp.22-25
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• 2001

A thyristor switch circuit for capacitor discharge application, of which the equivalent circuit includes a resistor between cathode and gate of a reverse-conducting thyristor and an avalanche diode anti-parallel between its anode and gate to set thyristor tum-on voltage, is monolithically integrated by planar process with AVE double-implantation method. To ensure a lower breakdown voltage of the avalanche diode for thyristor tum-on than the break-over voltage of the thyristor, $p^+$ wells on thyristor p base layer are made by boron implantation/drive-in for a steeper doping profile with higher concentrations while rest p layers of thyristor and free-wheeling diode parts are formed with Al implantation/drive-in for a doping profile of lower steepness. The free-wheeling diode part is isolated from the thyristor part by formation of separated p-well emitter for suppressing commutation between them, which is achieved during the formation of thyristor p-base layer.

• Archives of Pharmacal Research
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• 제20권4호
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• pp.358-362
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• 1997

Metabolite identification and urinary and biliary excretion of the new fluoroquinolone antibacterial agent DW116 [1-(5-fluoro-2-pyridyl)-6-fluoro-7-(4-methyl-1 -piperazinyl)-1, 4-dihydro-4-oxoquinoline-3-carboxylic acid, hydrochloride] after oral administration have been studied in Sprague-Dawley rats. The excretion kinetics were monoexponential. Most of the drug was eliminated via the hepatic and renal routes. Mean renal clearance of DW116 was 73.4 ml/hr/kg and mean biliary clearance was 83.8 ml/hr/kg. The major metabolite excreted in the bile was identified as the glucuronide ester of the parent drug using base-hydrolysis of the conjugate metabolite followed by co-HPLC with standard compound, $^{19}$ F-NMR and LC-MS methods. The glucuronide conjugate was also found in urine. The mean urinary recoveries of free and total (free plus glucuronide ester) DW116 were $28.6{\pm}2.7% $and $36.4{\pm}1.8%$ of the administered dose and the corresponding biliary recoveries were $14.4{\pm} 5.5%$ and $37.0{\pm}7.6%$, respectively.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.193-193
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• 2013

실리콘 박막 태양전지는 광 흡수층에서 형성된 정공과 전자를 효과적으로 분리하기 위해 p형과 n형으로 도핑된 층을 형성하는 p-i-n구조를 갖게 된다. 이러한 도핑 층을 형성하기 위해 B2H6와 PH3와 같은 독성 가스를 사용하기 때문에, 공정 안정성과 환경적인 이슈가 대두된다. 또한 도핑은 추가적으로 실리콘 박막 태양전지의 안정화 효율을 지속적으로 저하시키는 요인이 된다. 이러한 문제점을 개선하기 위하여, 창층으로 MoO3, V2O5, WO3 등과 같이 높은 일함수를 갖는 전이금속 산화물을 사용하고, 광 흡수층으로 i-Si:H을, 후면 전극으로 낮은 일함수를 나타내는 LiF/Al을 사용하였다. 전이금속 산화물과 LiF/Al의 큰 일함수 차이에 의해서 흡수층인 i-Si:H 에서 생성된 캐리어들은 효과적으로 분리되고 수집이 된다. 금속 산화물은 스퍼터링 공정에 의하여 이루어졌으며, 스퍼터링 공정조건에 따라 산화도가 조절되며, 이러한 산화도에 따라 태양전지의 셀 특성이 결정된다. 도핑 층이 없는 새로운 형태의 실리콘 박막 태양전지는 기존 비정질 실리콘 박막 태양전지에 비해 높은 안정화 효율을 나타내며, 이는 도핑 층이 없기 때문에 기존 실리콘 박막 태양전지의 열화현상에 따른 효율저하가 발생하지 않는 장점을 지내고 있다.

• Journal of Korean Vacuum Science & Technology
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• 제3권1호
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• pp.49-53
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• 1999

We have studied the field emission characteristics of diamond-like-carbon (DLC) films deposited by a layer-by-layer technique using plasma enhanced chemical vapor deposition, in which the deposition of a thin layer of DLC and a CH4 plasma exposure on its surface were carried out alternatively. The hydrogen-free DLC can be deposited by CH4 plasma exposure for 140 sec on a 5 nm DLC layer. N2 gas-phase doping in the CH4 plasma was also carried out to reduce the work function of the DLC. The optimum [N2]/[CH4] flow rate ratio was found to be 9% for the efficient electron emission, at which the onset-field was 7.2 V/$\mu\textrm{m}$. It was found that the hydrogen-free DLC has a stable electron emitting property.

• Transactions on Electrical and Electronic Materials
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• 제14권3호
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• pp.148-151
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• 2013

The control of Ga doping in ZnO nanowires (NWs) by physical vapor deposition has been implemented and characterized. Various Ga-doped ZnO NWs were grown using the vapor-liquid-solid (VLS) method, with Au catalyst on c-plane sapphire substrate by hot-walled pulsed laser deposition (HW-PLD), one of the physical vapor deposition methods. The structural, optical and electrical properties of Ga-doped ZnO NWs have been systematically analyzed, by changing Ga concentration in ZnO NWs. We observed stacking faults and different crystalline directions caused by increasing Ga concentration in ZnO NWs, using SEM and HR-TEM. A $D^0X$ peak in the PL spectra of Ga doped ZnO NWs that is sharper than that of pure ZnO NWs has been clearly observed, which indicated the substitution of Ga for Zn. The electrical properties of controlled Ga-doped ZnO NWs have been measured, and show that the conductance of ZnO NWs increased up to 3 wt% Ga doping. However, the conductance of 5 wt% Ga doped ZnO NWs decreased, because the mean free path was decreased, according to the increase of carrier concentration. This control of the structural, optical and electrical properties of ZnO NWs by doping, could provide the possibility of the fabrication of various nanowire based electronic devices, such as nano-FETs, nano-inverters, nano-logic circuits and customized nano-sensors.

• 한국분말재료학회지
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• 제17권5호
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• pp.399-403
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• 2010

The effects of $MnO_2$ doping on the crystal structure, ferroelectric, and piezoelectric properties of (K,Na)$NbO_3$ (KNN) ceramics have been investigated. $MnO_2$ was found to be effective in enhancing the densification and grain growth during sintering. X-ray diffraction analysis indicated that Mn ions substituted B-site Nb ions up to 2 mol%, however, further doping induced unwanted secondary phases. In comparison with undoped KNN ceramics, the well developed microstructure and the substitution to B-sites in 2 mol% Mn-doped KNN ceramics resulted in significant improvements in both piezoelectric coupling coefficient and electromechanical quality factor.

• 한국전자파학회논문지
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• 제12권2호
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• pp.293-298
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• 2001

Polyaniline(EB)/NMP 용액에 carbonblack, grahpite Ag를 첨가하여 우수한 막질의 free standing film을 제조하였다. 1 mole HCI로 도핑된 polyaniline(ES) free standing film($\sigma$=5 S/cm, t=0.14 mm)을 제조하여 10 MHz~1 GHz의 주파수 영역에서 전자기파 차폐효과를 측정한 결과 23~25 dB의 차폐효율을 나타내었으며, carbonblack, grahpite, AG을 첨가하여 제조한 ES free standing film 과 camphorsulfonic acid(CSA)를 도핑한 polyaniline film의 전자기파 차폐효율 측정결과 각각 30~34dB, 36~42dB, 44~52dB, 34~43dB로 ES free standing film 보다 우수한 특성을 나타내었다.