• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1584-1586
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• 2002

CuIn$Se_2$ (CIS) and related compounds such as Cu($In_xGa_{1-x})Se_2$(CIGS) have been studied by their potential for use in photovoltaic devices. CIS thin film materials which have high absorption coefficient and wide bandgap, have attracted much attention as an alternative to crystalline and amorphous silicon solar cells currently in use. Cu-rich CIGS film have very low resistivity, due to coexistence of the semimetallic $Cu_{2-x}Se$. In-rich CIGS films show high resistivity, since these films are compensated films without the $Cu_{2-x}Se$ phase. Optical properties of the CIGS films also change in accordance with the resistivity for the Cu/(In+Ga) ratio. The Cu-rich films have different spectra from In-rich films in near infrared wavelengths.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.50.2-50.2
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• 2018

The demand for steady and dependable power sources is very high in the field of sustainable energy because of the limited amount of fossil fuels reserves. Among several sustainable alternatives, solar energy may be the most efficient solution because it constitutes the largest renewable energy source. So far, the only practical way to store such large amounts of energy has been to use a chemical energy carrier likewise a fuel. In various solar energy to power conversion systems, the photoelectrochemical (PEC) splitting of water into hydrogen and oxygen by the direct use of solar energy is an ideal process. It is a renewable method of hydrogen production integrated with solar energy absorption and water electrolysis using a single photoelectrode. Previous studies on photoelectrode films for PEC water splitting cells have been mainly focused on synthesizing oxide semiconductors with wide band gaps, such as TiO2(3.2eV), WO3(2.8eV), and Fe2O3(2.3eV). Unfortunately, these pristine oxide photoanodes without any catalysts have relatively low photocurrent densities because of the inherent limitation of insufficient visible light absorption due to the wide bandgap. Specifically, there is a tradeoff between high photocurrent and photoelectrochemical corrosion behavior, which is representative of figures of meritf or PEC materials.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.462-462
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• 2013

Gallium Oxide (Ga2O3) has been widely investigated for the optoelectronic applications due to its wide bandgap and the optical transparency. Recently, with the development of fabrication techniques in nanometer scale semiconductor materials, there have been an increasing number of extensive reports on the synthesis and characterization of Ga2O3 nano-structures such as nano-wires, nanobelts, and nano-dots. In contrast to typical vaporliquid-solid growth mode with metal catalysts to synthesis 1-dimensional nano-wires, there are several difficulties in fabricating the nanostructures by using sputtering techniques. This is attributed to the fact that relatively low growth temperatures and higher growth rate compared with chemical vapor deposition method. In this study, Ga2O3 chestnut burr were synthesized by using radio-frequency magnetron sputtering method. In contrast to typical sputtering method with sintered ceramic target, a Ga2O3 powder (99.99% purity) was used as a sputtering target. Several samples were prepared with varying the growth parameters, especially he growth time and the growth temperature to investigate the growth mechanism. Samples were characterized by using XRD, SEM, and PL measurements. In this presentation, the details of fabrication process and physical properties of Ga2O3 nano chestnut burr will be reported.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.675-675
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• 2013

CIGS thin films have received a great attention as a promising material for solar cells due to their high absorption coefficient, appropriate bandgap, long-term stability, and low cost production. CIGS thin films have been deposited by various methods such as co-evaporation, sputtering, spray pyrolysis and electro-deposition. In this study, Cu(In,Ga)Se2(CIGS) thin films were prepared using a single quaternary target by rf magnetron sputtering. The effect of sulfurization on the structural, compositional and electrical properties of the films was examined in order to develop the deposition process. An optimal sulfurization process will be selected for the preparation of CIGS thin films with good structural, optical and electrical properties by applying various sulfurization processes. In addition, the electrical properties of CIGS thin films were investigated by post-deposition annealing process. The carrier concentration of CIG(SSe) thin films after sulfurization was increased from $10^{14}cm^{-3}$ to $10^{16}cm^{-3}$ and the resistivity was increased from 10 ${\Omega}cm$ to $10^3$ ${\Omega}cm$. It is confirmed that CIG(SSe) thin films prepared at optimal deposition condition have similar atomic ratio to the target value after sulfurization.

• 한국전기전자재료학회논문지
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• 제11권7호
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• pp.527-534
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• 1998

Thin film deposition of InN, which is a less-studied III-nitride compound semiconductor because of the difficulty if crystal growth, was performed by rf reactive sputtering method using In target and $N_2$reactive gas. The structrual, electrical, and optical properties of the produced films were measured and disussed according to the sputtering parameters such as deposition pressure, rf power, and substrate temperature. From the result of deposition pressure, rf power, and substrate temperature, we could obtain optimal conditions of 5m Torr, 60W, $60^{\circ}C$ for preparing InN thin film with high crystallinity, low carrier concentration, and high Hall mobility. The carrier concentration, Hall mobility, and optical bandgap of the fabricated InN thin films at optimal condition were $6.242\times10^{18}cm^{-3}, 212.526cm^2/V\cdot$ｓ, and 1.912eV, respectively.

• Applied Science and Convergence Technology
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• 제23권5호
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• pp.221-239
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• 2014

The global demand for energy has been increasing since past decades. Various technologies have been working to find a suitable alternative for the generation of sustainable energy. Photovoltaic technologies for solar energy conversion represent one of the significant routes for the green and renewable energy production. Despite of remarkable improvement in solar cell technologies, the generation of power is still suffering with lower energy conversion efficiency, high production cost, etc. The major problem in improving the PV efficiency is spectral mismatch between the incident solar spectrum and bandgap of a semiconductor material used in solar cell. Luminescent materials such as rare-earth doped phosphor materials having the quantum efficiency higher than unity can be helpful for photovoltaic applications. Quantum cutting phosphors are the most suitable candidates for the generation of two or more low-energy photons for the absorption of every incident high-energy photons. The phosphors which are capable of converting UV photon to visible and near-IR (NIR) photon are studied primarily for photovoltaic applications. In this review, we will survey various near IR quantum cutting phosphors with respective to their synthesis method, energy transfer mechanism, nature of activator, sensitizer and dopant materials incorporation and energy conversion efficiency considering their applications in photovoltaics.

• 센서학회지
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• 제5권6호
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• pp.60-67
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• 1996

저온 remote PECVD $SiO_{2}$막을 이용하여 제조된 InSb MIS구조에서의 계면의 전기적 특성에 대하여 연구하였다. $105^{\circ}C$에서 증착시킨 $SiO_{2}$막을 이용한 MIS구조의 중간 에너지 대역폭에서의 계면상태밀도가 $1{\sim}2{\times}10^{11}\;cm^{-2}eV^{-1}$으로 평가되었다. 그러나, $105^{\circ}C$이상의 고온에서 제조된 MIS소자의 계면에는 다량의 계면준위 및 트랩 준위가 존재하였다. G-V측정으로부터 계산된 계면준위들의 시상수는 $10^{-4}{\sim}10^{-5}\;sec$였으며, 증착온도가 증가할수록 트랩밀도가 증가하여 C-V특성곡선의 이력특성이 증대되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
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• pp.357-360
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• 2004

Al doped ZnO thin films have been were properties of excellent optical transmittance, low resistivity and wide bandgap where be widely used transparent electrode on solar cell. In this paper, ZnO:Al thin films on PC substrate were prepared by RF magnetron sputtering method using ceramic taget with diffrent deposition conditions. In addition, the electrical, structural, optical properties were investigated. we investigated sample properties of Sputter powers and pressures change in $25{\sim}125W,\;2{\times}10^{-2}{\sim}2{\times}10^{-3}Torr$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.144-145
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• 2006

ZnO is a promising material to make high efficiency violet or blue light emitting diodes (LEDs) for its large binding energy (60meV) and big bandgap. But the high quality p-type conduction of ZnO is a dilemma to achieve LEDs with it. In present study, we presented a reliable method to prepare ZnO thin films on (100)silicon substrates by RF magnetron sputtering in the mixture ambient of $N_2$ and $O_2$, accompanying with low pressure annealing in the sputtering chamber in $O_2$ at $600^{\circ}C$ and $800^{\circ}C$ respectively. X-ray diffraction and Hail effect with Van der Paul method were performed to test ZnO films. Seeback effect was also carried out to identify carrier types in ZnO films and showed the N-doped ZnO film annealed at $800^{\circ}C$ had achieved p-type conduction.

• Journal of the Korean Physical Society
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• 제73권11호
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• pp.1604-1611
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• 2018

Utilizing Sb-based bulk epilayers on large-scale low-cost substrates such as GaAs for fabricating infrared (IR) photodetectors is presently attracting significant attention worldwide. For this study, three sample series of $GaAs_xSb_{1-x}$, $In_{1-x}Ga_xSb$, and $InAs_xSb_{1-x}$ with different compositions were grown on semi-insulating GaAs substrates by using molecular beam epitaxy (MBE) and appropriate InAs quantum dots (QDs) as a defect-reduction buffer layer. Photoluminescence (PL) signals from these samples were observed over a wide IR wavelength range from $2{\mu}m$ to $12{\mu}m$ in agreement with the expected bandgap, including bowing effects. In particular, interband PL signals from $InAs_xSb_{1-x}$ and $In_{1-x}Ga_xSb$ samples even at room temperature show promising potential for IR photodetector applications.