• 한국재료학회지
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• 제5권3호
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• pp.297-309
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• 1995

본 연구에서는 이온선보조증착법에 의해 Si(100)기판위에 정합성장된 $Si_{0.5}$Ge_{0.5}$층의 핵성성과 성장을 고찰하였다. 성장층에 대한 AFM(Atomic Force Microscopy), RHEED(Reflection High Energy Electron diffraction) 등의 분석결과 Si(100)기판위에 이온선보조증착에 의하여 성장된 $Si_{0.5}$Ge_{0.5}$층은 Stranski-Kranstanov(SK)기구로 성장되며, 300eV, 10 $\mu$A/$cm^{2}$의 Ar이온선을 조사시키는 경우 결정성이 향상되었고, SK 성장 방식의 임계두께가 증가하였다. Ar 이온선 조사에 의해 MBE에 의한 정합성장온도(55$0^{\circ}C$-$600^{\circ}C$)보다 훨씬 낮은 20$0^{\circ}C$에서 정합성장이 가능하였으며, $x_{mn}$값은 10.5%로 MBE에 의한 정합성장시 보고된 $x_{mn}$ 값보다 낮았다. 이온충돌에 의해 발생한 3차원 island의 분해와 표면확산의 증가가 $Si_{0.5}$Ge_{0.5}$층의 성장에 현저한 영향을 미쳤으며, 이온충돌의 영향은 3차원 island의 생성보다 3차원 island의 분해가 더 안정한 낮은 증착온도에서만 관찰되었다.

• 한국자기학회지
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• 제20권6호
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• pp.212-215
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• 2010

비정질 Ga 박막은 벌크에 비해 높은 초전도 임계온도와 임계자기장 값을 보이나 그 특성은 불안정하여 상온에 한번 노출되면 그 초전도 특성을 잃어버리게 된다. 이 논문에서는 Ga/Al 두층 박막을 제작하여 이러한 비정질 Ga 박막의 불안정한 초전도 특성을 개선할 뿐만 아니라 기존의 스핀검출에 응용되고 있는 Al 박막을 대체할 수 있는 가능성을 연구하였다. 극초진공 분자빔박막 증착장비(UHV-MBE)를 사용하여 Ga/Al 두층 박막을 제작하고, 표면의 적절한 플라즈마 산화 처리에 의한 Ga/Al/$Al_2O_3$/Fe의 터널 접합구조를 제작하여 Ga/Al 박막의 초전도 특성을 측정하였다. 한편, Ga/Al 박막의 표면 특성은 Auger 전자 분광기를 이용하여 분석하였다.

• 한국재료학회지
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• 제27권4호
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• pp.221-228
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• 2017

Various morphologies of copper oxide (CuO) have been considered to be of both fundamental and practical importance in the field of electronic materials. In this study, using Cu ($0.1{\mu}m$ and $7{\mu}m$) particles, flake-type CuO particles were grown via a wet oxidation method for 5min and 60min at $75^{\circ}C$. Using the prepared CuO, AlN, and silicone base as reagents, thermal interface material (TIM) compounds were synthesized using a high speed paste mixer. The properties of the thermal compounds prepared using the CuO particles were observed by thermal conductivity and breakdown voltage measurement. Most importantly, the volume of thermal compounds created using CuO particles grown from $0.1{\mu}m$ Cu particles increased by 192.5 % and 125 % depending on the growth time. The composition of CuO was confirmed by X-ray diffraction (XRD) analysis; cross sections of the grown CuO particles were observed using focused ion beam (FIB), field emission scanning electron microscopy (FE-SEM), and energy dispersive analysis by X-ray (EDAX). In addition, the thermal compound dispersion of the Cu and Al elements were observed by X-ray elemental mapping.

• Journal of Electrochemical Science and Technology
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• 제13권4호
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• pp.417-423
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• 2022

With the emerging importance of catalysts for water electrolysis, developing efficient and inexpensive electrocatalysts for water electrolysis plays a vital role in renewable hydrogen energy technology. In this study, a 1nm thickness of TiC-supported Ru catalyst for hydrogen evolution reaction (HER) has been successfully fabricated using an electron (E)-beam evaporator and thermal decomposition of gaseous CH₄ in a furnace. The prepared Ru/TiC catalyst exhibited an outstanding performance for alkaline hydrogen evolution reaction with an overpotential of 55 mV at 10 mA cm^-2. Furthermore, we demonstrated that the outstanding HER performance of Ru/TiC was attributed to the high surface area of the support and the metal-support interaction.

• 한국진공학회지
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• 제1권1호
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• pp.43-49
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• 1992

표면구조 분석장치의 하나인 RHEED(Reflection High Energy Electron Diffraction) 장치를 설계.제작하였다. 전자선의 에너지는 0에서 20keV까지 연속가변이 가능하도록 하였 으며 전자선의 접속은 자기렌즈를 이용하였다. 이 장치를 본 연구실에서 제작한 초고진공용 기에 장착하여 K, Cs/Si(111)계의 표면구조를 분석하였다. 깨끗한 Si(111)7 $\times$ 7 표면을 가 지는 기판의 온도를 상온 및 20$0^{\circ}C$ ~ $700^{\circ}C$에서 K와 Cs를 증착시켰을 때 변화하는 표면 구조를 RHEED로 관찰하였다. K의 경우, 상온에서 Si(111)7 $\times$ 7-K, $300^{\circ}C$~$550^{\circ}C$에서 3 $\times$ 1 및 $550^{\circ}C$ 이상에서 1 $\times$ 1 구조가 관측되었고, Cs의 경우는 상온에서 $250^{\circ}C$까지는 1 $\times$ 1, $300^{\circ}C$에서 $\sqrt{3}{\times}\sqrt{3}$, $350^{\circ}C{\sim}400^{\circ}C$에서 $\sqrt{3}{\times}\sqrt{3}+3{\times}1$ 구조가 관측되었다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 춘계학술대회
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• pp.719-721
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• 2012

본 시험은 군전자장비의 전원제어부품으로 사용되는 TPS54315소자에 대하여 과도방사선에 따른 과도응답특성인 Upset/Latch-up특성을 평가하기 시험으로 포항가속기 연구소내의 Test LINAC 조사시설을 이용하여 $1.43{\times}10^7$rad(si)/sec~$1.25{\times}10^8$rad(si)/sec 선량률 조건에서의 실측시험을 수행하였다. 시험결과 $1.0{\times}10^8$rad(si)/sec 이후 Latch-up 현상이 확인되었으며 연속펄스 인가 시 Latch-up상태에서 정상상태로 복귀하는 결과를 확인하였다. 또한 이러한 현상은 과도방사선에 의한 광전류가 내부전원 Reset로직을 트리거 시킴으로써 Latch-up상태에서의 전원바이어스를 일시적으로 차단함에 따라 발생된 것으로 본 실험을 통하여 Reset회로가 내장된 소자의 경우 일부 Latch-up현상과 동시에 Reset회로가 트리거 되는 경우 Latch-up상태에서 정상상태로 복귀되는 결과를 확인하였다.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1996년도 The 9th KACG Technical Annual Meeting and the 3rd Korea-Japan EMGS (Electronic Materials Growth Symposium)
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• pp.508-508
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• 1996

;The growth of films have considerable interest in the field of superlattice structured multi-layer epitaxy led to realization of new devices concepts. Molecular beam epitaxy (MBE) with in situ observation by reflection high-energy electron diffraction (RHEED) is a key technology for controlled layered growth on the atomic scale in oxide crystal thin films. Also, the combination of radical oxygen source and MBE will certainly accelerate the progress of applications of oxides. In this study, the growth process of single crystal films using by MBE method is discussed taking the oxide materials of Bi-Sr-Ca-Cu family. Oxidation was provided by a flux density of activated oxygen (oxygen radicals) from an rf-excited discharge. Generation of oxygen radicals is obtained in a specially designed radical sources with different types (coil and electrode types). Molecular oxygen was introduced into a quartz tube through a variable leak valve with mass flowmeter. Corresponding to the oxygen flow rate, the pressure of the system ranged from $1{\;}{\times}{\;}10^{-6}{\;}Torr{\;}to{\;}5{\;}{\times}{\;}10^{-5}$ Torr. The base pressure was $1{\;}{\times}{\;}10^{-10}$ Torr. The growth of Bi-oxides was achieved by coevaporation of metal elements and oxygen. In this way a Bi-oxide multilayer structure was prepared on a basal-plane MgO or $SrTiO_3$ substrate. The grown films compiled using RHEED patterns during and after the growth. Futher, the exact observation of oxygen radicals with MBE is an important technology for a approach of growth conditions on stoichiometry and perfection on the atomic scale in oxide. The oxidization degree, which is determined and controlled by the number of activated oxygen when using radical sources of two types, are utilized by voltage locked loop (VLL) method. Coil type is suitable for oxygen radical source than electrode type. The relationship between the flux of oxygen radical and the rf power or oxygen partial pressure estimated. The flux of radicals increases as the rf power increases, and indicates to the frequency change having the the value of about $2{\times}10^{14}{\;}atoms{\;}{\cdots}{\;}cm^{-2}{\;}{\cdots}{\;}S^{-I}$ when the oxygen flow rate of 2.0 seem and rf power 150 W.150 W.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.111-111
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• 2007

Further scaling the semiconductor devices down to low dozens of nanometer needs the extremely shallow depth in junction and the intentional counter-doping in the silicon gate. Conventional ion beam ion implantation has some disadvantages and limitations for the future applications. In order to solve them, therefore, plasma source ion implantation technique has been considered as a promising new method for the high throughputs at low energy and the fabrication of the ultra-shallow junctions. In this paper, we study about the effects of DC bias and base pressure as a process parameter. The diluted mixture gas (5% $PH_3/H_2$) was used as a precursor source and chamber is used for vacuum pressure conditions. After ion doping into the Si wafer(100), the samples were annealed via rapid thermal annealing, of which annealed temperature ranges above the $950^{\circ}C$. The junction depth, calculated at dose level of $1{\times}10^{18}/cm^3$, was measured by secondary ion mass spectroscopy(SIMS) and sheet resistance by contact and non-contact mode. Surface morphology of samples was analyzed by scanning electron microscopy. As a result, we could accomplish the process conditions better than in advance.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 추계학술발표대회
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• pp.35.1-35.1
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• 2011

New photovoltaic (PV) materials and manufacturing approaches are needed for meeting the demand for lower-cost solar cells. The prototypal thin-film photovoltaic absorbers (CdTe and $Cu(In,Ga)Se_2$) can achieve solar conversion efficiencies of up to 20% and are now commercially available, but the presence of toxic (Cd,Se) and expensive elemental components (In, Te) is a real issue as the demand for photovoltaics rapidly increases. To overcome these limitations, there has been substantial interest in developing viable alternative materials, such as $Cu_2ZnSnS_4$ (CZTS) is an emerging solar absorber that is structurally similar to CIGS, but contains only earth abundant, non-toxic elements and has a near optimal direct band gap energy of 1.4~1.6 ev and a large absorption coefficient of ${\sim}10^4\;cm^{-1}$. The CZTS absorber layers are grown and investigated by various fabrication methods, such as thermal evaporation, e-beam evaporation with a post sulfurization, sputtering, non-vacuum sol-gel, pulsed laser, spray-pyrolysis method and electrodeposition technique. In the present work, we report an alternative method for large area deposition of CZTS thin films that is potentially high throughput and inexpensive when used to produce monolithically integrated solar panel modules. Specifically, we have developed an aqueous chemical approach based on chemical bath deposition (CBD) with a subsequent sulfurization heat treatment. Samples produced by our method were analyzed by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, absorbance and photoluminescence. The results show that this inexpensive and relatively benign process produces thin films of CZTS exhibiting uniform composition, kesterite crystal structure, and good optical properties. A preliminary solar cell device was fabricated to demonstrate rectifying and photovoltaic behavior.

• 한국전기전자재료학회논문지
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• 제23권6호
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• pp.481-486
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• 2010

ENIG (electroless Ni immersion gold) is one of surface finishing which has been most widely used in fine pitch SMT (surface mount technology) and BGA (ball grid array) packaging process. The reliability for package bondability is mainly affected by interfacial reaction between solder and surface finishing. Since the behavior of IMC (intermetallic compound), or the interfacial reaction between Ni and solder, affects to some product reliabilities such as solderability and bondability, understanding behavior of IMC should be important issue. Thus, we studied the properties of ENIG with P contents (9 wt% and 13 wt%), where the P contents is one of main factors in formation of IMC layer. The effect of P content was discussed using the results obtained from FE-SEM(field-emission scanning electron microscope), EPMA(electron probe micro analyzer), EDS(energy dispersive spectroscopy) and Dual-FIB(focused ion beam). Especially, we observed needle type irregular IMC layer with decreasing Ni contents under high P contents (13 wt%). Also, we found how IMC layer affects to bondability with forming continuous Kirkendall voids and thick P-rich layer.