• 반도체디스플레이기술학회지
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• 제19권4호
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• pp.94-98
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• 2020

The core/shell of nanowires (NWs) with Cu-doped CdSe quantum dots were fabricated as an electron transport layer (ETL) for perovskite solar cells, based on ZnO/TiO2 arrays. We presented CdSe with Cu2+ dopants that were synthesized by a colloidal process. An improvement of the recombination barrier, due to shell supplementation with Cu-doped CdSe quantum dots. The enhanced cell steady state was attributable to TiO2 with Cu-doped CdSe QD supplementation. The mechanism of the recombination and electron transport in the perovskite solar cells becoming the basis of ZnO/TiO2 arrays was investigated to represent the merit of core/shell as an electron transport layer in effective devices.

• Bulletin of the Korean Chemical Society
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• 제22권2호
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• pp.205-209
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• 2001

Uniformly-doped silicon thin films were fabricated by ion beam sputter deposition. The thin films had four levels of copper dopant concentration ranging between 1 ${\times}$1019 and 1 ${\times}$ 1021 atoms/cm3 . Concentrations of Copper dopants were determined by the isotope dilution inductively coupled plasma mass spectrometry (ICP-MS) to provide certified reference data for the quantitative surface analysis by secondary ion mass spectrometry (SIMS). The copper-doped thin films were dissolved in a mixture of 1 M HF and 3 M HNO3 spiked with appropriate amounts of 65 Cu. For an accurate isotope ratio determination, both the detector dead time and the mass discrimination were appropriately corrected and isobaric interference from SiAr molecular ions was avoided by a careful sample pretreatment. An analyte recovery efficiency was obtained for the Cu spiked samples to evaluate accuracy of the method. Uncertainty of the determined copper concentrations, estimated following the EURACHEM Guide, was less than 4%, and detection limit of this method was 5.58 ${\times}$ 1016 atoms/cm3.

• Journal of Ceramic Processing Research
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• 제19권6호
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• pp.499-503
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• 2018

In this paper, cobalt embedded in nitrogen and sulfur co-doped carbon nanotubes (CoNSTs) were synthesized for oxygen reduction reaction (ORR) catalysts. The CoNSTs were prepared through a facile heat treatment method without any templates. Different amounts of the metal salt were employed to examine the physicochemical and electrochemical properties of the CoNSTs. The CoNSTs showed the bamboo-like tube morphology with the encased Co nanoparticles in the tubes. Through the x-ray photoelectron spectroscopy analysis, the catalysts exhibited different chemical states of the nitrogen and sulfur species. As a result, the CoNST performed high activity toward the ORR in an acidic condition with the onset potential of 0.863 V (vs. reversible hydrogen electrode). It was clearly demonstrated from the electrochemical characterizations that the quality of the nitrogen and sulfur species significantly influences the ORR activity rather than the total amount of the dopants.

• Mass Spectrometry Letters
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• 제12권1호
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• pp.26-30
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• 2021

The impurity concentration is a crucial parameter for semiconductor thin films. Evaluating the impurity distribution in silicon thin film is another challenge. In this study, we have investigated the doping concentration of boron in silicon thin film using time of flight secondary ion mass spectrometry in dynamic mode of operation. Boron doped silicon film was grown on i) p-type silicon wafer and ii) borosilicate glass using hot wire chemical vapor deposition technique for possible applications in optoelectronic devices. Using well-tuned SIMS measurement recipe, we have detected the boron counts 101~104 along with the silicon matrix element. The secondary ion beam sputtering area, sputtering duration and mass analyser analysing duration were used as key variables for the tuning of the recipe. The quantitative analysis of counts to concentration conversion was done following standard relative sensitivity factor. The concentration of boron in silicon was determined 1017~1021 atoms/㎤. The technique will be useful for evaluating distributions of various dopants (arsenic, phosphorous, bismuth etc.) in silicon thin film efficiently.

• 한국분말재료학회지
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• 제28권6호
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• pp.518-526
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• 2021

This review summarizes the recent progress in iron-oxide-based heat generators. Cancer treatment using magnetic nanoparticles as a heat generator, termed magnetic fluid hyperthermia, is a promising noninvasive approach that has gained significant interest. Most previous studies on improving the hyperthermia effect have focused on the construction of dopant-containing iron oxides. However, their applications in a clinical application can be limited due to extra dopants, and pure iron oxide is the only inorganic material approved by the Food and Drug Administration (FDA). Several factors that influence the heat generation capability of iron-oxide-based nanoparticles are summarized by reviewing recent studies on hyperthermia agents. Thus, our paper will provide the guideline for developing pure iron oxide-based heat generators with high heat dissipation capabilities.

• Nuclear Engineering and Technology
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• 제28권5호
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• pp.458-466
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• 1996

The effects of dopants on the modification of microstructure of UO$_2$ and UO$_2$-4wt%CeO$_2$ sintered pellets have been studied in hydrogen and $CO_2$/CO mixture atmospheres by using $Ta_2O_5$, TiO$_2$ and $Nb_2O_5$ as sintering additives. The dopant were added as oxide powders and homogenized by attrition milling. The mixed powders were pressed, and then sintered in hydrogen at 1$700^{\circ}C$ , or in oxidizing atmosphere using Controlled $CO_2$/CO mixtures at 125$0^{\circ}C$. Both density and microstructure of UO$_2$ are modified by the addition of dopants in reducing atmosphere. The sintered density is increased with $Ta_2O_5$ addition up to 0.33wt% and subsequently decreased with higher content of the additive. The effect on the densification and the gain growth are apparent with the addition of 0.24wt% $Nb_2O_5$. With 0.lwt% titania and 0.6wt% $Ta_2O_5$, the sintered density is decreased, but the grain size is increased. In oxidizing atmosphere, the grain sizes for UO$_2$ doped with the above additives are smaller than that for pure UO$_2$. The grain size of Ta or Nb-doped UO$_2$ is decreased with increasing $CO_2$/CO ratio, but that of pure UO$_2$or T-doped UO$_2$ is increased. A large portion of second phases is observed in UO$_2$ doped with 0.lwt% TiO$_2$ sintered in hydrogen atmosphere, while, in $CO_2$/CO atmospheres, the second phases or dopant agglomerates are not observed. For UO$_2$-4wt%CeO$_2$ mixed oxide, the effect of additives on the gain growth is not so much as that for the pure UO$_2$. This is attributed to the formation of clusters by dopant cations and Ce ions, so that the additives contribute to a lesser exent to the grain growth for the mixed oxide.

• 한국결정성장학회지
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• 제7권2호
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• pp.253-258
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• 1997

반도체화 첨가제인 $Y_2O_3$와 $Nb_2O_5$ 첨가랑 변화에 따른 PTCR $BaTiO_3$ 세라믹스의 결정구조 해석과 상전이 특성을 연구하기 위하여 ($Ba_{0.85}Ca_{0.15})TiO_3$ ＋ X m/o $Nb_2O_5$(Y m/o $Y_2O_3$) ＋ 0.08 w/o $Mn(NO_3)_2$ㆍ$6H_2O$ ＋ 0.25 w/o $SiO_2$ 계에서 X는 0.1 ~ 0.4로 Y는 0.2 ~ 0.4로 각각 변화시켜 실험을 수행하였다. $Nb_2O_5$의 첨가시 B-site 치환에 따라서 격자상수가 선형적으로 변화하다가 0.3 mol% 이상 치환할 경우 c 축의 격자상수가 급격히 감소함을 알 수 있었다. 이는 octahedron distortion둥의 원인으로 판단되며, 이러한 격자상수 변화는 상전이 온도 결과와도 잘 일치함을 확인할 수 있었다. 또한 $Y_2O_3$ 첨가의 경우 0.3 mol%가지는 A, B-site를 각각 치환하며 그 이상부터는 A-site 이온을 주로 치환하는 것을 격자상수 변화와 상전이 온도결과를 통해 알 수 있었으며, Rietveld 해석결과 $Y^{3+}$가 A-site 치환시 $Ba^{2＋}$와 $Ca^{2＋}$를 같은 비율로 치환한다는 것을 알 수 있었다.

• 한국세라믹학회지
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• 제39권9호
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• pp.896-901
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• 2002

FHD(Flame Hydrolysis Deposition)공정은 화염 형성에 관여하는 장비의 조건들과 그에 따른 다양한 공정인자에 의하여 박막의 조성이 결정되며, 증착된 막을 치밀화하는 첨가물의 증발로 인해 열처리공정에서 조성이 변화되므로 공정인자로부터 최종적인 광도파막의 조성을 예측하는 것은 매우 어렵다. 본 연구에서는 FHD 공정에서 첨가가스의 유량을 제어하여 박막의 조성 및 광학적 특성을 예측할 수 있는 공정 분석의 기초자료를 제공하기 위하여 FTIR(Fourier Transformation Infrared Spectroscopy)측정과 ICP-AES(Inductively Coupled Plasma-Atomic Emission Spectrometry)측정을 통해 실리카 막의 조성분석에 대한 연구를 수행하였다. FTIR 흡수 스펙트럼을 통해 실리카 막에 존재하는 Si-O, B-O band를 측정하고 정성적 농도변화를 관찰 하였고, ICP-AES를 통해 Boron의 농도를 정량적으로 측정하였다. 이 두 결과로부터 FTIR을 이용한 정량적 조성분석의 기초자료인 B-O band의 흡광계수를 구하였다.

• 멤브레인
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• 제13권3호
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• pp.162-173
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• 2003

폴리아닐린(polyaniline, PANI)과 도판트인 camphorsulfonic acid(CSA), dodecyl benzene sulfonic acid(DBSA)와 의몰비 변화에 따라 가상 n형 PANI을 제조하였다. FT-IR측정으로부터 도핑유무를 확인하였고, indium thin oxide(ITO)에 코팅하여 제조한 전극에 대해, 순환전압전류법과 교류임피던스법을 이용하여 도판트의 영향을 조사하였다. FT-IR과 순환전압전류법으로부터, 제조된 전극이 양이온의 도핑-탈도핑이 일어나는 가상 n형의 특성을 가짐을 확인하였다. 순환전압전류법에서 산화-환원 피크전류값은 PANI/DBSA에 비하여 PANI/CSA가 약 5 배정도 더 큰 결과를 보였다. 교류임피던스법으로부터, 두 전극 모두 이상적인 Randles의 등가회로와 유사한 거동을 보였다. 전하이동저항은 PANI/CSA에서 $1.14~1.09 k{\Omega}$으로 거의 일정한 값을 보였고, PANI/DBSA는 DBSA 몰 비에 증가에 따라 $27.73{\sim}8.37K{\Omega}$으로 감소하여 나타났다. 이중층용량 또한 PANI/CSA는 $13.47{\sim}14.59 {\mu}F$으로 거의 일정하였으나, PANI/DBSA는 DBSA 몰 비 증가에 따라 $0.49{\sim}l.20 {\mu}F$으로 증가를 보였다. 결과적으로 PANI/CSA의 전기적 특성이 더 좋았으나, 도판트의 몰 비 증가에 따른 특성은 PANI/CSA 전극은 거의 일정하였고, PANI/DBSA 전극은 전기적 활성이 좋아짐을 알 수 있었다.

• 한국재료학회지
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• 제2권5호
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• pp.375-382
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• 1992

Composite target(MoS$i_{2.3}$)으로 부터 Mo-silicide를 형성시, 단결정 실리콘 위에 P, B$F_2$불순물(5${\times}10^{15}ions/cm^2$)과 다결정 실리콘 위에 P 불순물(5${\times}10^{15}ions/cm^2$)을 이온 주입하여 아르곤 분위기에서 급속열처리(RTA)하였다. 열처리는 600-120$0^{\circ}C$ 온도구간에서 20초간 행하였다. Mo-silicide의 특성 및 불순물의 거동은 4-point probe, X선 회절분석, SEM, SIMS, $\alpha$-step을 통해 조사하였다. 80$0^{\circ}C$에서 부터 MoS$i_2가 형성되며 열처리 온도가 증가할수록 낮은 비저항간을 갖는 안정한 MoS$i_2로 결정화가 이루어진다. 또한 열처리 동안 단결정 실리콘과 다결정 실리콘에서 Mo-silicide층으로 불순물의 내부 확산은 거의 발생하지 않았다.