• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.535-536
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• 2013

본 연구에서는 DC/RF co-sputtering공법을 통해 제작한 In-Mo-O 투명 Mo doping 농도 및 열처리 온도에 따른 전기적, 광학적, 구조적 특성을 분석하고, 최적화된 In-Mo-O 투명전극을 유기태양전지(OPVs)와 유기발광다이오드(OLED)에 적용하여 그 가능성을 평가하였다. Mo doping 농도는 co-sputtering 공정 중 MoO3에 인가되는 radio-frequency (RF) power를 변화시켜 조절되었으며, 투명전극의 광학적 특성 및 전기적 특성 향상을 위해 성막 공정 후 급속 열처리 공정을 온도 별로 진행하였다. In-Mo-O 투명 전극은 Mo 도핑 농도에 영향을 받음을 확인할 수 있었고, 최적화된 Mo doping 파워에서 성막한 In-Mo-O 박막은 급속 열처리 공정 후 면저항 24.57 Ohm/square, 투과도 81.57% (400~1,200 nm wavelength)를 나타내었다. Bulk hetero-junction 기반의 고효율 유기태양전지와 유기발광다이오드 적용하기 위해 본 연구에서 제작된 IMO 투명전극의 구조적 특성, 결정성 및 표면특성은 x-ray diffraction (XRD), atomic force microscopy(AFM), field effect scanning electron microscopy (FE-SEM), High-resolution transmission electron microscopy (HRTEM) 분석을 통해 진행하였다. In-Mo-O 투명 전극상에 제작된 OLEDs와 OPV는 reference ITO 전극에 제작된 OLEDs/OPV와 비교할 때 유사하거나 향상된 특성을 나타내었으며 이는 In-Mo-O 박막이 OLED/OPV용 투명 전극으로 적용이 가능함을 말해준다.

• Journal of Integrative Natural Science
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• v.13 no.3
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• pp.87-91
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• 2020

Molybdenum carbide (MoC_x) thin films (TFs) were deposited by reactive radio frequency (rf) magnetron co-sputtering in high vacuum chamber. We compared the properties of MoC_x thin films as the rf power changed on C target. The result of alpha step measurement showed that the thickness of the MoC_x TFs varied from163.3 to 194.86 nm as C power was increased from 160 to 200 W. The crystallinity of MoC_x such as b-Mo₂C, Mo₂C, and diamond like carbon (DLC) structures were observed by XRD. The oxidation states of Mo and C were determined using high resolution XPS spectra of Mo 3d and C 1s were deconvoluted. Molybdenum was consisted of Mo, Mo⁴⁺, and Mo⁶⁺ species. And C was deconvoluted to C-Mo, C, C-O, and C=O species.

• Journal of Magnetics
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• v.17 no.4
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• pp.245-250
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• 2012

Ferromagnetic resonance and X-ray specular reflectivity measurements were performed on $Ni_{81}Fe_{19}/Ir_{20}Mn_{80}/Co_{90}Fe_{10}$ exchange bias trilayers, which were grown using the pulsed-DC magnetron sputtering technique on Si(100)/$SiO_2$(1000 nm) substrates, to investigate the evolution of the interface roughness and exchange bias and their dependence on the NiFe layer thickness. The interface roughness values of the samples decrease with increasing NiFe thickness. The in-plane ferromagnetic resonance measurements indicate that the exchange bias field and the peak-to-peak line widths of the resonance curves are inversely proportional to the NiFe thickness. Furthermore, both the exchange bias field and the interface roughness show almost the same dependence on the NiFe layer thickness. The out-of plane angular dependent measurements indicate that the exchange bias arises predominantly from a variation of exchange anisotropy due to changes in interfacial structure. The correlation between the exchange bias and the interface roughness is discussed.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.378.1-378.1
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• 2014

In this study, we investigated that the resistance switching characteristics of Nb-doped HfO2 films with increasing Nb doping concentration. The Nb-doped HfO2 based ReRAM devices with a TiN/Nb-doped HfO2/Pt/Ti/SiO2 were fabricated on Si substrates. The Nb-doped HfO2 films were deposited by reactive dc magnetron co-sputtering at $300^{\circ}C$ and oxygen partial ratio of 60% (Ar: 16sccm, O2: 24sccm). Microstructure of Nb-doped HfO2 films and atomic concentration were investigated by XRD, TEM, and XPS, respectively. The Nb-doped HfO2 films showed set/reset resistance switching behavior at various Nb doping concentrations. The process voltage of forming/set is decreased and whereas the initial current level is increased in doped HfO2 films. However, the switching properties of Nb-doped HfO2 were changed above the specific doping concentration of Nb. The change of resistance switching behavior depending on doping concentration was discussed in terms of concentration of non-lattice oxygen and micro-structure of Nb-doped HfO2.

• Korean Journal of Materials Research
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• v.4 no.5
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• pp.535-540
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• 1994

Thin film magnet was fabricated by radio frequency magnetron sputtering using $Nd_13/(Fe.Co)_{70}B_{17}$ alloy target and magnetic properties were investigated according to sputtering conditions from the metallurgical point of view. we could obtain the best preferred orientation of $Nd_2Fe_{14}B$ phase at substrate temperatures between $450^{\circ}C$ and $460^{\circ}C$ with the input power 150W, and thin films had the anisotropic magnetic properties. But, as the thickness of thin film increased, the c-axis orientation gradually tended to be disordered and magnetic properties also become isotropic. Just like Nd-Fe-B meltspun ribbon, the microstructure of thin film magnet was consisted of very find cell shaped $Nd_2Fe_{14}B$ phase and the second phase along grain boundary. While, domain structure showed maze patterns whose magnetic easy axis was was perpendicular to film plane of thin film. It was concluded from these results that the perpendicualr anisotropy in magnetization was attributed to the perpendicular alignment of very find $Nd_2Fe_{14}B$ grains in thin film.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.58.1-58.1
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• 2011

CIS(CuInSe2)계 화합물 태양전지는 높은 광흡수계수와 열적 안정성으로 고효율 태양전지 제조가 가능하여 태양전지용 광흡수층으로 매우 이상적이다. 미국 NREL에서는 이러한 CIGS 태양전지를 Co-evaporation 방법으로 제조 20%이상의 에너지 변환 효율을 달성하였다고 보고하였다. CIGS 태양전지의 경우 기존의 유리 기판 대신 유연한 철강 기판을 사용해 태양 전지를 flexible하게 제조 할 수 있다는 장점이 있다. 이러한 flexible 태양전지의 경우 기존의 rigid 태양전지의 적용분야 뿐만 아니라 BIPV, 선박, 장난감, 군용, 자동차등 더욱 더 많은 분야에 활용이 가능하다. 본 연구에서는 기존의 rigid한 기판인 soda lime glass와 flexible 기판인 stainless steel 기판으로 소자를 제조하여 효율을 비교 분석 및 stainless steel 기판의 표면 처리 방법에 따라서 표면 조도의 특성을 분석하여 stainless steel 기판별 효율 특성도 비교 분석 하였다. 후면전극으로는 약 $1{\mu}m$의 Mo를 DC Sputtering 방법을 이용하여 증착하였고, CIGS 광흡수층은 약 $2.5{\mu}m$의 두께로 미국의 NREL과 같은 3 stage 방식을 이용하여 광흡수층을 Co-Evaporation 방법으로 제조하였고, 버퍼층인CdS는 약 50nm의 두께로 CBD 방법으로 제조 하였으며, 창층인 ZnO는 약 500nm 두께로 RF Sputtering 방법으로 제조 하였고, 마지막으로 약 $1{\mu}m$ 두께의 Al 전면전극은 Thermal Evaporation 방법으로 제조 하였다. 소자의 물리적, 전기적 특성을 분석하기위해 FE-SEM, AFM, Solar Cell Simulator 분석을 실시하였다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.109.1-109.1
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• 2012

본 연구에서는 co-sputtering을 통한 $WO_3$와 $In_2O_3$ 타겟을 사용하여 $WO_3$ 파워에 따른 Tungsten(W)-doped $In_2O_3$ (IWO) 투명 전극의 전기적, 광학적, 구조적 특성을 연구하고 이를 활용한 유기태양전지(Organic Photovoltaics; OPVs)의 특성을 분석하였다. Tungsten의 doping 농도는 $WO_3$에 인가되는 Radio-frequency (RF) power를 5~30 W 까지 변화시켜 조절하였으며, Rapid Thermal Annealing (RTA) 후 열처리 공정을 통해 IWO 박막의 전기적, 광학적, 구조적 특성을 분석하였다. Hall measurement 및 UV/Vis spectrometry 분석을 통하여 가시광선 영역에서 80% 이상의 높은 투과율, $48\;cm^2\;V^{-1}\;s^{-1}$의 홀 이동도, 20 ${\Omega}/{\Box}$ 이하의 낮은 면저항과 $3.2{\times}10^{-4}\;{\Omega}-cm$의 비저항 값을 나타내었다. 최적화된 IWO 박막을 이용한 OPV 셀 특성은 fill factor(FF): 61.59 %, short circuit current($J_{SC}$): 8.84 $mA/cm^2$, open circuit voltage($V_{OC}$): 0.60 V, efficiency(PCE): 3.27 %로 ITO로 제작된 OPV 샘플과 비교하였을 때 ITO를 대체할 수 있는 고이동도의 새로운 투명 전극 재료로서의 가능성을 확인하였다.

• Journal of the Korean institute of surface engineering
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• v.45 no.6
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• pp.242-247
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• 2012

Yb-doped ITO (ITO:Yb) films were deposited on unheated non-alkali glass substrates by magnetron cosputtering using two cathodes (DC, RF) equipped with the ITO and $Yb_2O_3$ target, respectively. The composition of the ITO:Yb films was controlled by adjusting the RF powers from 0 W to 480 W in 120 W steps with the DC power fixed at 70 W. The ITO:Yb films had a higher crystallization temperature ($200^{\circ}C$) than that of the ITO films ($170^{\circ}C$), which was attributed to both larger ionic radius of $Yb^{3+}$ and higher bond enthalpy of $Yb_2O_3$, compared to ITO. This amorphous ITO:Yb film post-annealed at $170^{\circ}C$ showed a resistivity of $5.52{\times}10^{-4}{\Omega}cm$, indicating that a introduction of Yb increased resistivity of the ITO film. However, these amorphous ITO:Yb films showed a high etching rate, fine pattering property, and a very smooth surface morphology above the crystallization temperature of the amorphous ITO films (about $170^{\circ}C$). The transmittance of all films was >80% in the visible region.

• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.563-569
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• 1996

Degradation of $Zn_3N_2$ films is studied by using several analytical techniques. Polycrystalline $Zn_3N_2$ films prepared by reactie rf magnetron sputtering are kept in the air. Electrical and optical properties are measured by using van der Pauw technique and double-beam spectrometry. Structure and chemical bonding states are studied by X-ray diffraction(XRD), Fourier transfer infrared ray spectroscopy(FT-IR) and X-ray photoelectron specroscopy (XPS). Significant differences are observed in optical properties between the degraded film and the ZnO film. XRD analysis reveals that the degraded film contains very small ZnO grains because very weak and broad ZnO peaks are observed. XPS and FT-IR measurements reveal the formation of $Zn(OH)_2$ in the degraded film. The existence of N-H bonds in degraded films is exhibited from the N 1s spectra. $Zn_3N_2$ change into the mixture of ZnO, $Zn(OH)_2$ and an ammonium salt.

• Transactions on Electrical and Electronic Materials
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• v.17 no.1
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• pp.18-20
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• 2016

Transparent and conducting IGZO thin films were deposited by RF magnetron sputtering on thin Cu coated glass substrates to investigate the effect of a Cu buffer layer on the structural, optical, and electrical film properties. Although X-ray diffraction (XRD) analysis revealed that both the IGZO single layer and IGZO/Cu bi-layered films were in the amorphous phase, the IGZO/Cu films showed a lower resistivity of 5.7×10⁻⁴ Ωcm due to the increased mobility and high carrier concentration. The decreased optical transmittance of the IGZO/Cu films was also attributed to a one order of magnitude higher carrier concentration than the IGZO films. From the observed results, the thin Cu layer is postulated to be an effective buffer film that can enhance the opto-electrical performance of the IGZO films in transparent thin film transistors.