• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1997년도 추계학술대회 논문집
• /
• pp.525-528
• /
• 1997

In this study, Eu(TTA)$_3$(phen) was synthesized and its films were prepared by vapor deposition method. Its films were characterized by UV-Vis absorption spectroscopy, Atomic Force Microscopy(AFM) and Photoluminescence(PL) measurements. Their electroluminescent(EL) characteristics were investigated by PL measurements, where a cell structure of glass substrate/ITO/Eu(TTA)$_3$(phen)/Al was employed. It was found that its films were well prepared without any decomposition and the film thickness could be controlled by adjusting the amount of Eu(TTA)$_3$(phen) in a boat. The EL spectrum of these films was almost the same as that of PL spectrum of these films.

• 한국응용과학기술학회지
• /
• 제14권3호
• /
• pp.79-87
• /
• 1997

In this study, MEH-PPV was synthesized and MEH-PPV and its mixtures with PMMA were deposited on substrates with Langmuir-Blodgett(LB) technique and their photoluminescent char acteristics were investigated using UV-Vis absorption spectroscopy, and photoluminescence(PL) measurements. The surface morphology of the LB films of MEH-PPV and its mixture with PMMA were investigated using Atomic Force Microscopy(AFM). Electroluminescent devices using LB films were fabricated with Al and ITO as a top and bottom electrode, respectively, and their I-V characteristics were investigated.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.362-362
• /
• 2014

Atomic layer deposition (ALD) can be regarded as a special variation of the chemical vapor deposition method for reducing film thickness. ALD is based on sequential self-limiting reactions from the gas phase to produce thin films and over-layers in the nanometer scale with perfect conformality and process controllability. These characteristics make ALD an important film deposition technique for nanoelectronics. Tantalum pentoxide ($Ta_2O_5$) has a number of applications in optics and electronics due to its superior properties, such as thermal and chemical stability, high refractive index (>2.0), low absorption in near-UV to IR regions, and high-k. In particular, the dielectric constant of amorphous $Ta_2O_5$ is typically close to 25. Accordingly, $Ta_2O_5$ has been extensively studied in various electronics such as metal oxide semiconductor field-effect transistors (FET), organic FET, dynamic random access memories (RAM), resistance RAM, etc. In this experiment, the variations of chemical and interfacial state during the growth of $Ta_2O_5$ films on the Si substrate by ALD was investigated using in-situ synchrotron radiation photoemission spectroscopy. A newly synthesized liquid precursor $Ta(N^tBu)(dmamp)_2$ Me was used as the metal precursor, with Ar as a purging gas and $H_2O$ as the oxidant source. The core-level spectra of Si 2p, Ta 4f, and O 1s revealed that Ta suboxide and Si dioxide were formed at the initial stages of $Ta_2O_5$ growth. However, the Ta suboxide states almost disappeared as the ALD cycles progressed. Consequently, the $Ta^{5+}$ state, which corresponds with the stoichiometric $Ta_2O_5$, only appeared after 4.0 cycles. Additionally, tantalum silicide was not detected at the interfacial states between $Ta_2O_5$ and Si. The measured valence band offset value between $Ta_2O_5$ and the Si substrate was 3.08 eV after 2.5 cycles.

• Applied Science and Convergence Technology
• /
• 제25권3호
• /
• pp.56-60
• /
• 2016

The ALD process is an adequate technique to meet the requirements that come with the downscaling of semiconductor devices. To obtain thin films of the desired standard, it is essential to understand the thermal decomposition properties of the precursors. As such, this study examined the thermal decomposition properties of TEMAHf precursors and its effect on the formation of $HfO_2$ thin films. FT-IR experiments were performed before deposition in order to analyze the thermal decomposition properties of the precursors. The measurements were taken in the range of $135^{\circ}C-350^{\circ}C$. At temperatures higher than $300^{\circ}C$, there was a rapid decrease in the absorption peaks arising from vibration of $Sp^3$ C-H stretching. This showed that the precursors experienced rapid decomposition at around $275^{\circ}C-300^{\circ}C$. $HfO_2$ thin films were successfully deposited by Atomic Layer Deposition (ALD) at $50^{\circ}C$ intervals between $150^{\circ}C$ to $400^{\circ}C$; the deposited films were characterized using a reflectometer, X-ray photoelectron spectroscopy (XPS), Grazing Incidence X-ray Diffraction (GIXRD), and atomic force microscopy (AFM). The results illustrate the relationship between the thermal decomposition temperature of TEMAHf and properties of thin films.

• 대한치과보철학회지
• /
• 제37권2호
• /
• pp.212-234
• /
• 1999

Dental restorative materials must have the physical properties to withstand wear and corrosion. Base metal alloys possess better mechanical properties and lower price than the gold alloys. For these reasons such alloys have largely replaced the precious metal alloys. One aspect to con-sider is the release of metal substances to oral environment. The release of elements from dental alloys is a continuing concern because the elements may have the potentially harmful biological effects on local tissues. The purpose of this study was to minimize metal release on the nonprecious metal surfaces by ion beam assisted deposition(IBAD) of titanium nitride (TiN) Ni-Cr-Be alloys with and without TiN coatings were secured in an wear test machine opposing ruby ball to determine their relative resistance to wear with loom, 200m, 300m and 400m sliding distance. And the corrosion behavior of the Ni-Cr-Be alloys with and without TiN coatings and 3 dental noble alloys have been studied. Potentiodynamic curves were used to analyse the corrosion characteristics of the alloys. The measurement of the released Ni and Cr ions was conducted by analysis of the electrolyte solution with atomic absorption spectroscopy. The results were as follows : 1. The critical sliding distance that wore down TiN coatings of $2.5{\mu}m$ thickness in this study condition was 300m. 2. Ion beam assisted deposition of TiN showed a good surface modification with respect to the properties of wear and corrosion resistance. 3. X-ray diffraction showed that the strongest peak of TiN is TiN(111) in the coatings. 4. The release of Ni and Cr ions from alloys measured by means of atomic absorption spectroscopy was reduced by ion beam assisted deposition of TiN.

• 한국자기학회지
• /
• 제17권1호
• /
• pp.18-21
• /
• 2007

Pulsed laser deposition(PLD) 박막 증착법을 이용하여 hexagonal $HoMn_{1-x}-Fe_xO_3$(x=0.0, 0.05) 물질을 박막으로 $Pt/Ti/SiO_2/Si$ 기판 위에 증착하였다. 또한 x-ray diffraction(XRD), atomic force microscopy(AFM), scanning electron microscope(SEM), 및 x-ray photoelectron spectroscopy(XPS)를 통하여 박막의 결정학적 및 미세 구조를 분석하였고, conversion electron $M\"{o}ssbauer$ spectroscopy(CEMS)를 이용하여 자기적 특성에 관해 연구하였다. 결정구조는 hexagonal 구조로써 space group이 $P6_3cm$로 분석되었고, single crystal과는 달리 (110) 방향으로 우선 배향성을 가지고 증착되었다. $HoMn_{0.95}Fe_{0.05}O_3$ 박막의 경우 single crystal과 비교했을 때 hexagonal unit cell의 $c_0$ 축은 일정하나 $a_0$ 축은 다소 감소함으로 분석되었다. 이는 박막 증착에 사용된 $Pt/Ti/SiO_2/Si$ 기판과의 lattice mismatch 때문으로 해석된다. Fe가 미량 치환된 $HoMn_{0.95}Fe_{0.05}O_3$ 박막을 상온에서 CEMS 측정을 수행한 결과, $HoMn_{0.95}^{57}Fe_{0.05}O_3$ 분말의 경우 magnetic $T_N$이 72K 부근이므로, 상온에서 doublet absorption spectrum이 관측되었고, 전기사중극자 분열값(quadrupole splitting; ${\Delta}E_Q$)이 $1.62{\pm}0.01mm/s$로 비교적 큰 값을 가짐을 확인하였다.

• 분석과학
• /
• 제21권4호
• /
• pp.326-331
• /
• 2008

$Na_2CO_3$ 용액에서 DVB-amidoxime 수지에 대한 우라닐 이온의 분배계수를 측정하였다. 이때 분배계수 값은 수지의 입자크기가 작을수록 증가하였으며 최고 약 70 까지 나타났다. 0.0044 M $Na_2CO_3$ 용액에서 우라늄의 흡착능은 $3.4{\mu}mole$/g-resin 로나타났다. pH 9에서 pH 11 사이의 0.5 M $Na_2CO_3-NaHCO_3$ 용액에서 분배계수를 측정한 결과 pH 가 증가할 수록 분배계수 값이 증가하였으며, 또한 이 값은 순수한 $Na_2CO_3$ 용액에서의 분배계수 값 보다 낮은 값을 보였다. FTIR 흡수분광법을 이용하여 amidoxime 수지의 성능을 확인하였다. UV-Vis 흡수분광법을 이용하여 $UO_2(CO_3)_3^{-4}$ 의 4개의 흡수피크(400~500 nm)를 확인하였다. Amidoxime 수지가 충진된 분리관을 이용하여 핵분열생성물질로 부터 우라늄을 분리하였다. 그러나, 대부분의 우라늄 및 핵분열생성물질이 용출되고 소량만이 흡착되었다. 이것은 amidoxime 수지의 낮은 흡착 능 때문으로 생각된다.

• 광물과 암석
• /
• 제33권1호
• /
• pp.1-10
• /
• 2020

고압 환경에서 규산염 용융체의 원자 구조에 대한 정보는 지구 내부 마그마의 열전도율이나 주변 암석과의 원소 분배계수와 같은 이동 물성을 이해하는 단서를 제공한다. 규소의 전자 구조는 규산염 다면체 주변의 산소 원자 분포와 연관성을 가질 것으로 예상되나, 이 사이의 상관관계가 명확하게 밝혀져 있지 않다. 본 연구는 SiO₂의 고밀도화에 따른 규소의 전자 구조 변화의 미시적인 기원을 규명하기 위해 SiO₂ 동질이상의 규소 부분 상태 밀도와 L₃-edge X-선 흡수분광분석(X-ray absorption spectroscopy; XAS) 스펙트럼을 계산하였다. 규소의 전도 띠 영역에서 전자 구조는 결정 구조에 따라서 변화하였다. 특히 d-오비탈은 108, 130 eV 영역에서 배위 환경에 따른 뚜렷한 차이를 보였다. 계산된 XAS 스펙트럼은 규소 전도 띠의 s,d-오비탈에서 기인하는 피크를 보였으며, 결정 구조에 따라 s,d-오비탈과 유사한 양상으로 변화했다. 계산된 석영의 XAS 스펙트럼은 SiO₂ 유리의 XR S 실험 결과와 유사하였으며 규소 주변 원자 환경이 비슷하기 때문으로 생각된다. XAS 스펙트럼을 수치화한 무게 중심 값은 Si-O 결합 거리와 밀접한 상관관계를 가지며 이로 인하여 고밀도화 과정에서 체계적으로 변화한다. 본 연구의 결과는 Si-O 결합 거리에 민감한 규소 L_2,3-edge XRS가 규산염 유리 및 용융체의 고밀도화 기작을 규명하는 과정에서 유용하게 적용될 수 있음을 지시한다.

• 분석과학
• /
• 제12권4호
• /
• pp.299-305
• /
• 1999

Electrolyte as cathode glow discharge(ELCAD)는 용액 중에 포함된 미량 중금속을 연속 자동 측정하기 위한 새로운 플라스마 source로서 주로 원자방출법에 의하여 원소들을 측정한다. 그러나 수은의 경우 원자 방출법보다는 원자 흡수법을 주로 적용한다. 본 연구에서는 기존의 원자흡수분광기의 원자화부분을 ELCAD cell로 대치하여 원자흡수법에 의하여 수은을 측정하였다. 일반적으로 원자방출법에 의하여 원소들의 방출선측정시 용액의 pH가 1.0에서 가장 안정한 플라스마와 가장 큰 방출세기를 나타내었으나 수은인 경우 pH 3.0에서 가장 흡광도가 높았다. 그러나 플라스마의 안정도는 pH가 1.0 일 때가 가장 좋은 관계로 흡광도의 % RSD 값은 pH 1.5 용액에서는 0.35% 이었으며 pH 3.0인 검액에서는 3.6%를 나타내었다. 두 검액에 대해 각각 검량곡선을 작성하였을 때 모두 양호한 직선성을 보였으며, 각각의 검출 한계를 구한 결과, pH 1.5 용액은 약 40 ppb, pH 3.0 용액은 10 ppb level 이었다.

• Restorative Dentistry and Endodontics
• /
• 제19권1호
• /
• pp.1-26
• /
• 1994

The purpose of this study was to investigate the dissolution components during corrosion of amalgams and to identify surface corrosion products in the modified Fusayama artificial saliva. Four type of amalgam alloys were used: low copper lathe cut amalgam alloy (Cavex 68), low copper spherical amalgam alloy (Caulk Spherical Alloy), high copper admixed amalgam alloy (Dispersalloy) and high copper single composition amalgam alloy (Tytin). Each amalgam alloy and Hg were triturated according to the manufacturer's direction by means of mechanical amalgamator (Capmaster, S.S.White), and then the triturated mass was inserted into the cylindrical metal mold which was 10mm in diameter and 2.0mm in height and condensed with compression of 150kg/$cm^2$ using oil pressor. The specimens were removed from the mold and stored at room temperature for 7 days and cleansed with distiled water for 30 minutes in an ultrasonic cleaner. The specimens were immersed in the modified Fusayama artificial saliva for the periods of 1 month, 3 months and 6 months. The amounts of Hg, Cu, Sn and Zn dissolved from each amalgam specimen immersed in the artificial saliva for the periods of 1 month, 3 months and 6 months were measured using Inductivity Coupled Plasma Atomic Emission Spectrometry (ICPQ-1000, Shimadzu, Japan) and amount of Ag dissolved from amalgam specimen was measured using Atomic Absorption Spectrophotometry (Atomic Absorption/Flame emission spectrophotometer M-670, Shimadzu, Japan). A surface corrosion products of specimens were analysed using Electron Spectroscopy Chemical Analyser (ESCA PHI-558, PERKIN ELMER, U.S.A.). The secondary image and back scattered image of corroded surface of specimens was observed under the SEM, and the corroded surface of specimens was analysed with the EDX. The following results were obtained. 1. The dissolution amount of Cu was the most in high copper admixed amalgam(Dispersalloy) and the least in high copper single composition amalgam(Tytin). 2. Sn and Zn were dissolved during all the experiment periods, and dissolution amounts were decreased as the time elapsed. 3. Initial surface corrosion products were ZnO and SnO. 4. Corrosion of ${\gamma}$ and ${\gamma}_2$ phase in low copper amalgams was observed and Ag-Cu eutectic alloy phase was corroded in low copper spherical amalgam(Caulk Sperical Alloy). 5. Corrosion of ${\gamma}$ and $\eta$' phase in high copper amalgams was observed and Ag-Cu eutectic alloy phase was corroded in high copper admixed amalgam(Dispersalloy). 6. Sn-Cl was produced in the subsurface of low copper amalgams and high copper admixed amalgam.