• 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 Surface Engineering Conference
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• 2011.05a
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• pp.180-181
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• 2011

기존의 GaN LED에 사용되어지고 있는 p형 GaN 반도체의 Ni/Au 투명 접촉 전극을 제조할 때 발생하는 오염과 공정을 줄이고 발광효율을 향상시킬 수 있는 투명 접촉 전극을 제작하기 위해 마그네트론 2원 동시 방전법을 사용하여 AZO-NiO 박막을 증착 하였다. Al 원자 함량에 따른 AZO-NiO 박막의 구조적, 전기적, 광학적 특성을 조사하였다.

• Journal of the Korean Vacuum Society
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• v.14 no.2
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• pp.84-90
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• 2005

The influence of plasma parameters on the growth of $In_{0.2}Ga_{0.8}N/GaN$ heterostructures has been investigated using plasma-assisted molecular beam epitaxy. Since plasma ejects plenty of energetic particles with different energy levels and flux density at various rf power levels, plasma modulated both growth rate and optical properties significantly. For instance, surface roughness and the emission spectrum of photoluminescence were degraded at low and high rf power. According to sharp interfaces between epitaxial films and strong peaks observed from photoluminescence spectra, our experimental setup presented optimal operation range of rf powers at around 400W. The phenomena could be explained by the presence of energetic particles modulating the rate of plasma stimulated desorption and surface diffusion, and energetic particles exceeding critical value resulted in the incorporation of defects at subsurface. The optimal rf power regime increased by 100W for $In_{0.2}Ga_{0.8}N/GaN$ growth in comparison with GaN. The effects of rf power were discussed in conjunction with kinetic processes being stimulated by energetic particles.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.96.2-96
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• 2003

• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.115.1-115
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• 2002

• Proceedings of the Korean Vacuum Society Conference
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• 2008.08a
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• pp.98-98
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• 2008

• Korean Journal of Materials Research
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• v.10 no.10
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• pp.691-697
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• 2000

$Al_xGa_{1-x}N$ thin layers are promising materials for optical devices in the UV regions. $Al_xGa_{1-x}N$ thin layers w were grown on sapphire substrates by metalorgaruc chemical vapor deposition (MOCVD). The molar Al fraction and crystallinity of layers were deduced from synchrotron x-ray scattering experiment. Surface morphology were investigated using SEM and SPM. $Al_xGa_{1-x}N$ layers crystallinity were related with undoped GaN crystallinity. The Al mole fraction of $Al_xGa_{1-x}N$ layers affect the surface morphology of $Al_xGa_{1-x}N$ layers. The surface morphology was rough­e ened and the cracks were obse$\pi$ed by increasing the Al mole fractions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.8
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• pp.775-779
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• 2006

In this study, sputtered $Al_2O_3$ thin films were evaluated as a passivation layer in the process of InGaN-based blue LEDs in order to improve the brightness of LED lamps. In terms of packaged LED lamps, lamps with $Al_2O_3$ passivation layer emanated higher brightness than those with $SiO_2$ passivation layer, and LED lamps with 90 nm $Al_2O_3$ passivation layer were the brightest among four kinds of lamps. Although lamps with $Al_2O_3$ passivation had a slight increase in operating voltage, their brightness was improved about 13.6 % compare to the lamps made of conventional LEDs without the changes of emitting wavelength.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.37-39
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• 1996

A hydride vapor phase epitaxy (HVPE) method was performed to prepare the GaN thick-films on c-plane sapphire substrates. The full-width at half maximum of double crystal X-ray rocking curve from 350${\mu}{\textrm}{m}$ thick GaN was 576 arcsecond. The photo- luminescence spectrum measured (at room temperature) show the narrow bound exciton(I$_2$) line and weak donor-acceptor pair recombination peak, however, there was not observed deep donor-acceptor pare recombination indicate the GaN crystals prepared in this study are of high purity and high crystalline quality.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.573-573
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• 2012

High quality $VO_2$ thin films were successfully grown on GaN substrate by optimizing oxygen partial pressure during the growth using RF sputtering technique. The $VO_2$ thin film grown on GaN substrate exhibited an unusual metal insulator transition behavior, which was known to be observed only either in doped sample or under uniaxial stress. Raman spectra also confirmed that metal insulator transition occurred from monoclinic M1 to rutile R phase via monoclinic M2 phase with increasing temperature. We believe that large lattice mismatch between $VO_2$ and GaN substrate may cause M2 phase to be thermodynamically stable. Optical transmittance and its electrical switching behavior were carefully investigated to elucidate the underlying physics of its metal insulator transition behavior. This study may lead to a unique opportunity to better understand the growth mechanism of M2 phase dominant $VO_2$ thin films.