• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.888-890
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• 1999

ZnO thin films on (001) sapphire substrates have been deposited by pulsed laser deposition using a Nd:YAG laser with the wavelength of 355 nm at an oxygen pressure of 350 mTorr. In order to investigate the effect of the substrate temperature on the properties of ZnO thin films, the experiment has been performed at various substrate temperatures in the range of $200^{\circ}C$ to $700^{\circ}C$. According to XRD, (002) textured ZnO films of high crystalline quality have been obtained by pulsed laser deposition technique. However, the intensity of UV emission is mostly depending on the stoichiometry of ZnO films.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.54-57
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• 2004

ZnO thin films on (001) sapphire substrates have been deposited by pulsed laser deposition(PLD) technique using an Nd:YAG laser with a wavelength of 266 m. During deposition, the experiment of the deposition of ZnO thin films has been performed for substrate temperatures in the range of $400^{\circ}C$ and flow rate of 350 sccm, films have been annealed at various substrate temperatures after deposition. After post-annealing treatment in the oxygen ambient, the structural properties of ZnO thin films were characterized by diffraction (XRD), SEM and the optical of the ZnO were characterized by photoluminescence (PL).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.95-98
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• 1999

ZnO thin films on (001) sapphire substrates have been deposited by pulsed laser deposition technique using a Nd:YAG laser with the wavelength of 355 nm. In order to investigate the effect of the deposition conditions on the properties of ZnO thin films at an oxygen pressure of 350 mTorr, the experiment has been Performed at various substrate temperatures in the range of 20$0^{\circ}C$ to $700^{\circ}C$. According to XRD, (002) textured ZnO films of high crystalline quality have been obtained and the intensity of UV emission was the highest at 40$0^{\circ}C$ substrate temperature.

• Journal of the Korean Vacuum Society
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• v.16 no.6
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• pp.479-482
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• 2007

InN nanograins were directly grown on $0.3^{\circ}$-miscut (toward M-plane) c-plane sapphire substrates by hydride vapor phase epitaxy (HVPE) and their growth characteristics were investigated by utilizing x-ray scattering. Depending on the various growth parameters, the formation of InN was sensitively influenced. Six samples were grown by changing HCl flow rate, the substrate temperature and Ga/In source zone temperature. All the samples were grown on unintentionally $NH_3-pretreated$ sapphire substrates. By increasing the flow rate of HCl from 10 sccm to 20 sccm, the formation of GaN grains with different orientations was observed. On the other hand, when the substrate temperature was raised from $680^{\circ}C$ to $760^{\circ}C$, the increased substrate temperature dramatically suppressed the formation of InN. A similar behavior was observed for the samples grown with different source zone temperatures. By decreasing the source zone temperature from $460^{\circ}C$ to $420^{\circ}C$, a similar behavior was observed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05a
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• pp.127-130
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• 2005

The properties of phosphorus doped ZnO multilayer thin films deposited on (001) sapphire substrates by pulsed laser deposition (PLD) were investigated by using annealing treatment at various annealing temperature after deposition. The phosphorus doped ZnO multilayer was composed of phosphorus doped ZnO layer and two pure ZnO layers on sapphire substrate. The structural. electrical and optical properties of the ZnOthin films were measured by X-ray diffraction (XRD). Hall measurements and photoluminescence (PL). As the annealing temperature optimized. the electrical properties of the ZnO multilayer showed a electron concentration of $1.56{\times}10^{16}/cm^3$, a resistivity of 17.97 ${\Omega}cm$. It was observed the electrical property of the film was changed by dopant activation effect as thermal annealing process

• Journal of the Korean Vacuum Society
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• v.13 no.3
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• pp.103-108
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• 2004

High-quality ZnO films were grown on sapphire (001) substrates by the atomic layer epitaxy (ALE) technique using DEZn as a Zinc precusor and $H_2O $ as an oxidant at both $170^{\circ}C$ and $400^{\circ}C$ which are in the ALE and the CVD process temperature ranges, respectively. The films were annealed in an oxygen atmosphere in the temperature range from 600 to 100$0^{\circ}C$ for an hour and then investigate photoluminescence (PL) properties using He-Cd laser. PL intensity tends to increases as the annealing temperature increase for both the annealed ZnO films grown at $170^{\circ}C$ and $400^{\circ}C$ , while PL did not nearly occur at the as-deposited ones. The PL intensity of the ZnO film grown at $400^{\circ}C$ is low after it is annealed at high temperature owing to a large number of Zn-Zn bonds although it has increased in the visible light wavelength region after annealing. In contrast the PL intensity has increased significant in the visible light region after annealing

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1627-1630
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• 2004

ZnO thin films on (001) sapphire substrates have been deposited by pulsed laser deposition(PLD) technique using an Nd:YAG laser with a wavelength of 266nm. Before post-annealing treatment in the oxygen ambient, the experiment of the deposition of ZnO thin films has been performed for substrate temperatures in the range of $300{\sim}450^{\circ}C$ and flow rate of 100${\sim}$700 seem. In order to investigate the effect of post-annealing treatment of ZnO thin films, films have been annealed at various temperatures after deposition. After post-annealing treatment in the oxygen ambient, the structural properties of ZnO thin films were characterized by X-ray diffraction(XRD) and the optical properties of the ZnO were characterized by photoluminescence(PL).

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.2
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• pp.103-106
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• 2000

ZnO is a wide-bandgap II-IV semiconductor and has a variety of potnetial applications. ZnO exhibits good piezoelectric, photoelectric and optical properties, and is a good candidate for an electroluminescence device. ZnO films have been deposited on (001) sapphire by PLD technique. Nd:YAG pulsed laser was operated at a wavelength of $\lambda=355nm$. The ZnO films were deposited at oxygen pressures from base to 500 mTorr. The substrate temperatures was increased from $200^{\circ}C\; to\;700^{\circ}C$ films showed strong UV emission by increasing the partial oxygen pressure. We have investigated the relationship between partial oxygen pressure and the intensity of UV emission.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.3
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• pp.103-108
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• 2005

ZnO thin films on (001) sapphire substrates have been deposited by pulsed laser deposition(PLD) technique using an Nd:YAG laser with a wavelength of 266nm. Before post-annealing treatment in the oxygen ambient, the experiment of the deposition of ZnO thin films has been performed for substrate temperatures in the range of $300\~450^{\circ}C$ and oxygen gas flow rate of $100\~700\;sccm$. In order to investigate the effect of post-annealing treatment of ZnO thin films, films have been annealed at various temperatures after deposition. After post-annealing treatment in the oxygen ambient, the structural properties of ZnO thin films were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM) and the optical properties of the ZnO were characterized by photoluminescence(PL).

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.4
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• pp.164-167
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• 2010

Bulk GaN single crystal with 1.5 mm thickness was successfully grown by hydride vapor phase epitaxy (HVPE) technique. Free-standing GaN substrates of $10{\times}10,\;15{\times}15$ mm size were fabricate after lift-off of sapphire substrate and their optical properties were characterized properties for device applications. X-ray diffraction patterns showed (002) and (004) peak, and the FWHM of the X-ray rocking curve (XRC) measurement in (002) was 98 arcsec. A sharp photoluminescence spectrum at 363 nm was observed and defect spectrum at visible range was not detected. The hexagonal-shaped etch-pits are formed on the GaN surface in $200^{\circ}C\;H_3PO_4$ at 5 minutes. The defect density calculated from observed etch-pits on surface was around $5{\times}10^6/cm^2$. This indicates that the fabricated GaN substrates can be used for applications in the field of optodevice, and high power electronics.