• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.238-238
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• 2012

Ag (silver)의 일함수는 T-OLED (Top Emission Organic Light Emitting Diode)의 전극소자로 사용하기에는 다소 낮다는 단점이 있다(~4.3 eV). 이러한 단점을 해결하기 위한 대안으로 Ag 박막의 표면을 플라즈마 처리, UV 처리 및 열처리를 통하여 일함수를 높이는 연구가 진행 되어왔다(>5.0 eV). 하지만 현재의 대부분 연구는 후 처리된 박막의 일함수에 초점을 맞춰 연구가 진행 되어 박막의 nano-mechanical property에 대한 연구는 매우 부족하다. 따라서 본 논문에서는 AgOx 박막의 nano-mechanical property에 초점을 맞춰 분석을 실시하였다. 연구에 사용된 샘플은 Ag 박막을 유리기판 위에 rf-magnetron sputter 장치를 이용하여 100 W의 power로 150 nm 두께로 증착하였다. 증착된 Ag 박막은 $O_3$ 발생 UV 램프를 이용하여, 다양한 시간동안 UV 처리하였다(0~9분). 증착된 샘플은 Four-point probe, nanoindenter 장비를 이용하여 nano-mechanical property를 분석하였다. 실험 결과 UV 처리 시간이 0, 1분에서 면저항이 0.16, 0.50 ${\Omega}$/sq로 급격한 변화가 나타났으나, 반면 3분 이후 9분의 샘플의 경우, 0.55 ${\Omega}$/sq에서 0.24, 0.20, 0.15 ${\Omega}$/sq로 감소하여 전기적 특성변화를 볼 수 있었다. 또한 nanoindenting 결과 UV 처리한 박막의 극 표면 경도 값의 변화는 0~5분 처리한 샘플의 경우, 물리적인 경도가 증가하는 형태를 보이며 UV 처리를 5분간 했을때 7.89 GPa로 최고의 경도를 가진다. 그 이후부터는 6.97, 3.46 GPa의 결과로 박막의 경도가 감소되는 결과를 얻었다. 이러한 결과로부터 Ag 박막의 후처리에 따른 Ag 물질의 산화 및 결정상태에 따라 박막 내에 존재하는 residual stress를 분석할 수 있다.

• 정보저장시스템학회논문집
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• 제8권2호
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• pp.39-43
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• 2012

In spite of many advantages, the practical application of the thin film solar cell is restricted due to its low efficiency compared with the bulk type solar cells. This study intends to adopt the surface plasmon effect using nano particles to solve the low efficiency problem in thin film solar cells. By inserting Ag nano-particles in the absorbing layer of a thin film solar cell, the poynting vector value of the absorbing layer is increased due to the strong energy field. Increasing the value may give thin film solar cells chance to absorb more energy from the incident beam so that the efficiency of the thin film solar cell can be improved. In this work, we have designed the optimal shape of Ag nano-particle in the absorbing laser of a basic type thin film solar cell using the finite element analysis commercial package COMSOL. Design parameters are set to the particle diameter and the distance between each Ag nano-particle and by changing those parameters using the full factorial design variable set-up, we can determine optimal design of Ag nano-particles for maximizing the poynting vector value in the absorbing layer.

• 한국진공학회지
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• 제21권1호
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• pp.12-16
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• 2012

Top-Emitting OLED (Organic Light-Emitting Diode) 디스플레이에서는 반사율이 가장 높은 Ag (silver) 박막이 쓰이고 있지만, 소자에서 요구되는 일함수(work function)가 상대적으로 낮기 때문에 전극과 유기물간에 에너지 장벽이 발생하여 발광효율을 낮추는 요인이 되고 있다. 본 논문에서는 Ag 전극의 일함수를 높이기 위한 연구를 진행하였으며, 박막 형태의 Ag 전극에 대하여 nanotribology 접근법으로 연구를 실행하였다. Ag는 rf magnetron sputter를 이용해 glass 위에 증착한 후 furnace에서 $300^{\circ}C$, 30분간 대기 중에서 열처리하였고, 또 다른 시료는 표면에 산소 상압플라즈마로 처리 시간(30, 60, 90, 120s)을 각기 다르게 하여 시료를 제조하였다. Ag 전극을 nanoindentation을 통해 국부 영역에 대한 물리적 특성의 변화를 측정하였고, Kelvin probe force microscopy을 이용해 시료 표면의 포텐셜을 측정했다. 그 결과 열처리한 시료의 포텐셜값은 가장 크게 증가하였지만 균일도가 낮아졌다. 120s 플라즈마 처리한 시료는 불완전한 산화막의 생성으로 인해 탄성계수 및 경도값과 박막의 Weibull modulus를 극히 낮게 만들었지만, 60s, 90s 플라즈마 처리는 시료의 균일도를 높이고 또한 포텐셜을 증가시켜 T-OLED 성능 개선에 좋은 영향을 미치게 될 것이다.

• 한국환경보건학회지
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• 제39권4호
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• pp.369-375
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• 2013

Objectives: This study was conducted to identify factors determining the toxicity of manufactured silver nano-particles (AgNPs) on aquatic organisms. Methods: For this purpose, we prepared several AgNPs with varied characteristics, including hydrodynamic size (nano-$^{ABC}Ag^{Cit}\;vs$-sized-$^{ABC}Ag^{Cit}$), impurities ($^{ABC}Ag$ stock vs $^{ABC}Ag$), and citrate capping ($^{ABC}Ag^{Cit}$), using a commercially available manufactured AgNP ($^{ABC}Ag$ stock). Acute tests were conducted using larval zebrafish (Danio rerioI). In addition, in order to determine the ecotoxicological potentials of various capping agents, toxicity tests were conducted with microbes, waterfleas, and fish for eight different capping agents that are used for NPs. Results: The toxicity of AgNPs in terms of 96 h fish $LC_{50}$ increased in the following order: $^{ABC}Ag$ stock < $^{ABC}Ag=^{ABC}Ag^{Cit}=nano-^{ABC}Ag^{Cit}$ < ${\mu}$-sized-$^{ABC}Ag^{Cit}$ < $AgNO_3$. After removing impurities by dialysis, 96 h $LC_{50}$ value decreased significantly from $126.6{\mu}g/L$ (95% confidence intervals [CI]: 107.0-146.2) ($^{ABC}Ag$ stock) to $78.6{\mu}g/L$ (CI: 72.7-84.8) ($^{ABC}Ag$). For ${\mu}$-sized-$^{ABC}Ag^{Cit}$ (ranging between 3.9 and 40.6 nm) and $^{ABC}Ag^{Cit}$ (40.6 nm and $9.1{\mu}m$), the 96 h $LC_{50}$ of the former ($43.9{\mu}g/L$, CI: 36.0-51.7) was approximately two-fold lower than that of the latter ($87.0{\mu}g/L$, CI: 73.5-100.3). Conclusions: In this study, we found that for acute lethality, the contribution of impurities and particle size was significant, but that of citrate was negligible.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.381-382
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• 2007

IZO/Ag/IZO (IAI) anode films for flexible organic light emitting diodes (OLEDs) were grown on PC (polycarbonate) substrate using DC sputter (IZO) and thermal evaporator (Ag) systems as a function of Ag thickness. To investigate electrical and optical properties of IAI stacked films, 4-point probe and UV/Vis spectrometer were used, respectively. From a IAI stacked film with 12nm-thick Ag, sheet resistance of $6.9\;{\Omega}/{\square}$ and transmittance of above 82 % at a range of 500-550 nm wavelength were obtained. In addition, structural and surface properties of IAI stacked films were analyzed by XRD (X-ray diffraction) and SEM (scanning electron microscopy), respectively. Moreover, IAI stacked films showed dramatically improved mechanical properties when subjected to bending both as a function of number of cycles to a fixed radius. Finally, OLEDs fabricated on both flexible IAI stacked anode and conventional ITO/Glass were fabricated and, J-V-L characteristics of those OLEDs were compared by Keithley 2400.

• Journal of Microbiology and Biotechnology
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• 제18권8호
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• pp.1482-1484
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• 2008

Spherical silver nanoparticles (nano-Ag) were synthesized and their antifungal effects on fungal pathogens of the skin were investigated. Nano-Ag showed potent activity against clinical isolates and ATCC strains of Trichophyton mentagrophytes and Candida species ($IC_{80}$, 1-7${\mu}g/ml$). The activity of nano-Ag was comparable to that of amphotericin B, but superior to that of fluconazole (amphotericin B $IC_{80}$, 1-5${\mu}g/ml$; fluconazole $IC_{80}$, 10-30${\mu}g/ml$). Additionally, we investigated their effects on the dimorphism of Candida albicans. The results showed nano-Ag exerted activity on the mycelia. Thus, the present study indicates nano-Ag may have considerable antifungal activity, deserving further investigation for clinical applications.

• 한국분말재료학회지
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• 제8권3호
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• pp.192-196
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• 2001

Ag doped Hydroxyapatite powder in nano-scale was successfully synthesized either by co-precipitation or by ion exchange route. The fabricated powder was successfully dispersed through freeze drying due to the prevention of secondary particles. The antimicrobial effects of nano-HAp against E.coli was superior to micron ones not only in its strength but also in duration.

• 한국초전도ㆍ저온공학회논문지
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• 제5권3호
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• pp.6-10
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• 2003

Silver nano-powder was added to Ma $B_2$ to make (Ag)$_{(x)wt.%}$(Mg $B_2$)$_{(l00-x)wt.%}$ (A $g_{x}$-Mg $B_2$) (10 $\leq$ x $\leq$ 50) composite superconductors to investigate the effect of the Ag nano-powder on the vortex pinning. Pellets made out of the mixed powder were put inside stainless steel tubes, which were sintered at 85$0^{\circ}C$ in Ar atmosphere. No impurity phase was identified for as-rolled samples. However, both the Mg $B_2$ and the A $g_{x}$-Mg $B_2$ composite pellets, when sintered, contain small amount of Mg $B_4$ and MgAg impurity phases. From the magnetization study, it was found that the flux pinning was improved in the high magnetic field region (> 3 T) only when 10w/o Ag was added to Mg $B_2$. The "two step" structures in ZFC M(T) curve gradually increased as the amount of Ag added increased. Pinning centers can be created by adding a suitable amount of Ag nano-powder which is not too large to increase the decoupling between the Mg $B_2$ grains.crease the decoupling between the Mg $B_2$ grains.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 초전도 자성체
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• pp.3-6
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• 2002

Effect of Ag additive element on microstructure of $Fe_{87-x}Zr_7B_6Ag_x$, magnetic thin films on Si(001) substrates has been investigated using Transmission Electron Microscopy(TEM) and X-ray Diffraction(XRD). All samples with additive Ag element were made by DC-sputtering and subjected to annealing treatments of $300^{\circ}C{\siim}600^{\circ}C$ for 1 hr. TEM and XRD showed that perfectly amorphous state in Ag-free Fe-based films was observed in as-deposited condition. The as-deposited Fe-based films with the presence of Ag constituent have a mixture of Fe-based amorphous and nano-sized Ag crystalline phases. In this case, additive element, Ag was soluted into Fe-based matrix. With the increase in additive element, Ag, insoluble nano-crystalline Ag particles were dispersed in the Fe-based amorphous matrix. Crystallization of Fe-based amorphous phase in the matrix of $Fe_{82}Zr_7B_6Ag_5$ thin films occurred at an annealing temperature of $400^{\circ}C$. Upon annealing, the amorphous-Ag crystalline state of Fe-Zr-B-Ag films was transformed into the mixture of Ag crystalline phase + Fe-based amorphous phase + ${\alpha}$-Fe cluster followed by the crystallization process of ${\alpha}$-Fe nanocrystalline + Ag crystalline phases.

• 대한화학회지
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• 제57권5호
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• pp.618-624
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• 2013

코어-쉘 형태의 금@은 나노입자가 재구성된 자기조립 블록공중합체 역마이셀 박막에 선택적으로 결합하여 특정 클러스터 배열을 형성하도록 유도하였고, 생성된 배열에 대하여 나노입자 사이의 상호작용에 따른 국소 표면 플라즈몬 결합 현상을 고찰하였다. 금@은 나노입자 배열을 제조하기 위해 폴리스티렌-블록-폴리(4-비닐피리딘) 역마이셀 박막을 주형으로 선택하였으며, 특정 용매 처리에 의해 선택적으로 유도되는 역마이셀 박막의 재구성 현상을 바탕으로, 폴리비닐피롤리돈으로 안정화된 금@은 나노입자의 도입 방법에 따라 규칙적이거나 무질서한 두가지 유형의 금@은 나노입자의 배열을 제조하였다. 금@은 나노입자를 안정화시키기 위하여 사용한 리간드 종류, 금 코어와 은 쉘의 결합, 은 쉘의 두께 변화, 및 금@은 나노입자의 배열 형태 등의 다양한 변수에 따라 발현되는 국소 표면 플라즈몬 결합 현상을 자외선-가시광 흡광 스펙트럼으로 관찰하였다. 최종적으로 나노입자 배열을 표면 증강 라만 산란 현상을 고찰하기 위한 기판으로써 응용하였으며 금@은 나노입자 패턴의 결합 정도에 상응하는 현저히 증강된 라만 신호를 관찰하였다.