• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.380-380
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• 2010

The chalcopyrite $ZnIn_2S_4$ epilayers were grown on the GaAs substrate by using a hot-wall epitaxy (HWE) method. The crystal field and the spin-orbit splitting energies for the valence band of the $ZnIn_2S_4$ have been estimated to be 0.1541 eV and 0.0129 eV, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the ${\Delta}so$ definitely exists in the $\Gamma_5$ states of the valence band of the $ZnIn_2S_4$/GaAs epilayer. The three photocurrent peaks observed at 10 K are ascribed to the $A_{1^-}$, $B_{1^-}$, and $C_1$-exciton peaks for n = 1. Also, we obtained the $A_{\infty^-}$ and B-exciton peaks from the PC spectrum at 293 K.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.140-140
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• 2000

The effects of partial pressures of various gases on the qualities of coated conductors are studied, where the long samples were fabricated in a vacuum of a large physical vapour deposition system. The various gases such as $0_25,$H_2$,H_20$,$C_n H_m$, and CO come out from the large heating system and gives somewhat complicated effects on the interfacial chemistry at CeO/Ni which Is Important for the epitaxial growth of the film. The results of XRD measurements on the films fabricated in the controlled partial pressures of thoes gases will be presented.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.424-427
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• 2003

We have investigated the microstructural analysis of epitaxial lateral overgrowth (ELO), pendeoepitaxy (PE), and superlattice structures used as technology for the reduction of structural defects like dislocation in nitride semiconductors using transmission electron microscopy. We confirmed that the regrowth process such as ELO and PE is very effective technique on the reduction of threading dislocation (less than $10^6/cm^2$) in the specific area. However, to decrease the defect density in the whole nitride films and the suppress the generation of defect by regrowth, we should find the optimized conditions. Besides, the process using double PE and AlGaN/GaN superlattice structure showed no effect on the defect reduction up to now.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.59-60
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• 2005

The characteristics of GaN epitaxial layers grown on silicon (111) substrates by metalorganic vapor phase epitaxy have been investigated. The only control of AIN thickness was found to decrease the stress sufficiently for avoiding crack formation in an overgrown thick ($2.6{\mu}m$) CaN layer. X-ray diffraction measurementsare used to determine the effect of AIN thickness on the strain in the subsequent GaN layers. The 437arcsec linewidth on the (002) x-ray rocking curve also attest the high crystalline quality of GaN on Si (111).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.72-75
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• 1996

A hydride vapor phase epitaxy (HVPE) method is performed to prepare the GaN thin films on c-plane sapphire substrate. The full-width at half maximum of double crystal X-ray rocking curves from 20$\mu\textrm{m}$-thick GaN was 576 arcsecond. The photoluminescence spectrum measured 10 K shows the hallow bound exciton (I$_2$) line and weak donor-acceptor peak, however, there was not observed deep donor-acceptor pair recombination indicate the GaN crystals prepared in this study are of high purity and high crystalline quality. The GaN layer is n-type conducting with electron mobility of 72 $\textrm{cm}^2$/V$.$sec and with carrier concentration of 6 x 10$\^$18/cm/sup-3/.

• Proceedings of the Korean Vacuum Society Conference
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• 2003.02a
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• pp.89-89
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• 2003

• Journal of the Korean Vacuum Society
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• v.4 no.3
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• pp.319-326
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• 1995

초고진공에서 Si(100)-2X1 기판 위에 Pt를 약 100$\AA$의 두께로 증착한 후 in-situ로 열처리하는 고상에피택셜 성장법으로 PtSi 박막을 형성시켰다. XRD와 XPS 분석 결과 $200^{\circ}C$로 열처리한 시료에서는 Pt3Si, Pt2Si와 PtSi의 상이 섞여 있었으나 50$0^{\circ}C$로 열처리한 시료에서는 PtSi의 단일상만 확인되었으며, 형성된 PtSi 박막은 주상구조와 판상구조의 이중구조를 나타내었다. 기판 온도를 $500^{\circ}C$로 유지하면서 Pt를 증착한 후 $750^{\circ}C$에서 열처리한 경우에는 판상구조를 갖는 양질의 PtSi 박막이 에피택셜 성장되었다. HRTEM분석 결과 에피텍셜 성장된 PtSi와 기판 Si(100)의 계면은 PtSi[110]//Si[110], ptSi(110)//Si(100)의 정합성을 가졌다. 판상구조를 갖는 PtSi상의 에피택셜 방향은 기판과 열처리 온도에는 의존하나 열처리 시간에는 무관한 것으로 나타났다.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.47.2-47.2
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• 2011

High-efficient transparent conductive oxide (TCO) film-embedding Si heterojunction solar cells were fabricated. An improved crystalline indium-tin-oxide (ITO) film was grown on an Al-doped ZnO (AZO) template upon hetero-epitaxial growth. This double TCO-layered Si solar cell provided significantly enhanced efficiency of 9.23 % as compared to the single TCO/Si devices. The effective arrangement of TCO films (ITO/AZO) provides a good interface, resulting in the enhanced photovoltaic performances. It discusses TCO film arrangement scheme for efficient TCO-layered heterojunction solar cells.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.11
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• pp.1014-1018
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• 2005

The purpose of this study is to obtain strong bond strength at the interface between piezoelectric substrates and semiconductor thin films to be applied for the manufacture of high-performance acoustic wave semiconductor coupled device. For this purpose, we have compared and examined the effects of different surface treatment methods on hydrophile properties at the surface of the piezoelectric substrates. Moreover, we have observed the effect of microwave and laser on the elimination of water molecules at the interface. As for the piezoelectric substrates, dry method for surface treatment was found to be superior in the control of hydrophilicity of the surface compared to wet method. On the other hand, both microwave and laser were found to be effective in the elimination of water molecules in the interface.

• ETRI Journal
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• v.27 no.6
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• pp.677-684
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• 2005

A phased array antenna was fabricated using four-element ferroelectric phase shifters with a coplanar waveguide (CPW) transmission line structure based on a $Ba_{0.6}Sr_{0.4}TiO_3(BST)/MgO$ structure. Epitaxial BST films were deposited on MgO (001) substrates by pulsed laser deposition. To attain the large differential phase shift and small losses for a ferroelectric CPW phase shifter, an impedance-matching-part adding technique between the effective transmission line and connecting cable was used. The return loss and insertion loss for this techniqueadapted BST CPW device were improved with respect to those for a normal BST CPW device. For an X-band phased array antenna system consisting of ferroelectric BST CPW phase shifters, power divider, dc block, patch antenna, and programmed dc power, the steering beam could be tilted by $15^{\circ}$ in either direction.