• 한국진공학회:학술대회논문집
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• 한국진공학회 2007년도 제33회 하계학술대회 초록집
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• pp.68-68
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• 2007

• 한국재료학회:학술대회논문집
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• 한국재료학회 2002년도 추계학술발표강연 및 논문개요집
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• pp.23-23
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• 2002

• 한국재료학회:학술대회논문집
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• 한국재료학회 1998년도 IUMRS-ICEM ABSTRACT BOOK
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• pp.43.1-43
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• 1998

• JSTS:Journal of Semiconductor Technology and Science
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• 제6권3호
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• pp.199-205
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• 2006

Patterned sapphire substrates (PSS) were fabricated by a simple wet etching process with $SiO_2$ stripe masks and a mixed solution of $H_2SO_4$ and $H_3PO_4$. GaN layers were epitaxially grown on the PSS under the optimized 2-step growth condition of metalorganic vapor deposition. During the 1st growth step, GaN layers with triangular cross sections were grown on the selected area of the surface of the PSS, and in the 2nd growth step, the GaN layers were laterally grown and coalesced with neighboring GaN layers. The density of threading dislocations on the surface of the coalesced GaN layer was $2{\sim}4\;{\times}\;10^7\;cm^{-2}$ over the entire region. The epitaxial structure of near-UV light emitting diode (LED) was grown over the GaN layers on the PSS. The internal quantum efficiency and the extraction efficiency of the LED structure grown on the PSS were remarkably increased when compared to the conventional LED structure grown on the flat sapphire substrate. The reduction in TD density and the decrease in the number of times of total internal reflections of the light flux are mainly attributed due to high level of scattering on the PSS.

• 전자공학회논문지D
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• 제36D권5호
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• pp.63-68
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• 1999

본 논문에서는 저압 유기 금속 화학증착법으로 성장시킨 GaN박막들을 실온 케소드루미네슨스 방법으로 광학적 특성을 측정하여 결정성장 메커니즘과 광학적 특성과의 관계를 규명하였다. 관측된 스펙트럼은 주로 364nm의 강한 band-edge emission 피크와 550nm의 깊은 준위 피크이었다. 빔 전류의 증가에 따라 364nm 스펙트럼의 세기가 깊은 준위 발광 스펙트럼보다 크게 증가시켰다. 이는 성장 초기 GaN박막의 결정 결함이 깊은 준위 발광 스펙트럼과 깊은 관계가 있음을 나타내 주고 있다. 또한 미세 결정 구조와 깊은 준위 발광 스펙프럼과의 관계 분석을 위해 주사형 전자현미경 사진과 캐소드루미네슨스 스펙트럼을 비교 검토하였다.

• Journal of Photoscience
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• 제7권1호
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• pp.27-30
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• 2000

The Photoluminescence (PL) measurement results of a very good quality GaN sample grown by metalorganic chemical vapor deposition (MOCVD) are reported. The temperature dependences of peak position, emission intensity, and the full width at half maximum (FWHM) of free-exciton (FX) A and B are presented. Our results show the fast thermal quenching of FX transition intensities and predominantly acoustic phonon scattering of emission line broadening. The transition-energy-shift following the Varshni's empirical equation, and by using it to fit the data, E$\_$A1/(T) = 3.4861 eV -6.046 $\times$ 10$\^$-4/T$^2$ (620.3+ T) eV, E$\_$B1/(T) = 3.4928 eV -4.777 $\times$ 10$\^$-4/T$^2$ / (408.2+ T) eV and E$\_$A2/ = 3.4991 eV -4.426 $\times$ 10$\^$-4/ T$^2$ / (430.6+ T) eV for A(n=1), B(n=1), and A(n=2) are obtained respectively.

• Applied Microscopy
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• 제27권4호
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• pp.483-488
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• 1997

A misfit dislocation generation in InAs epilayers grown on (001) InP substrates (oriented $2^{\circ}$ off (001) toward the [110] direction) using metalorganic chemical-vapor deposition was studied. The InAs film of 17 nm thickness grown at $405^{\circ}C$ showed the three different arrays of dislocations: a straight orthogonal array to the <110> direction, an array to the >100> direction, and an array tilted by a degree of $5\sim45^{\circ}$ from the [110] direction. All of the dislocations had a/2<101> Burgers vectors inclined $45^{\circ}$ to the interface. Upon annealing at $660^{\circ}C$ the InAs films with 60, 140 and 220 nm thicknesses, most of the misfit dislocations became the Lomer type $(\sim100%)$ oriented exactly along the >110> direction. These misfit dislocation spacings were decreased with increasing the InAs thickness up to 220 nm thickness. This phenomena was interpreted by the relationship between the dislocation interaction energy among parallel misfit dislocations and the opposite remnant InAs epilayer strain energy. The distance between misfit dislocations was measured by transmission electron microscopy.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.91-94
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• 2002

Textured Ce$O_{2}$ buffers for YBCO coated conductors were deposited on biaxially textured Ni substrate by metalorganic chemical vapor deposition The texture of deposited Ce$O_{2}$ films was varied with deposition temperature(T) and oxygen partial pressure($Po_{2}$). ($\ell$ 00) textured Ce$O_{2}$ films were deposited at T= 500~$520^{\circ}C$, $Po_{2}$= 0.90~3.33 Torr. The growth rate of the Ce$O_{2}$ films was 150~200 nm/min at T= $520^{\circ}C$ and $Po_{2}$= 2.30 Torr, which was much faster than that prepated by other physical deposition method.

• The Korean Journal of Ceramics
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• 제6권3호
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• pp.219-223
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• 2000

The ferroelectric SBT films were deposited on Pt/Ti/SiO$_2$/Si substrates by liquid injection metalorganic chemical vapor deposition (MOCVD) with single-mixture solution of Sr[Ta(OEt)$_5$(dmae)]$_2$and Bi(C$_6$ 6/H$_5$)$_3$. The Sr/Ta and Bi/Ta ratio in SBT films depended on deposition temperature and mol ratio of precursor in the single-mixture solution. At the substrate temperature of 40$0^{\circ}C$, Sr/Ta and Bi/Ta ratio were close to 0.4 and 1 at precursor mol ratio of 0.5~1.0, respectively. As-deposited film was amorphous. However, after annealing at 75$0^{\circ}C$ for 30 min in oxygen atmosphere, the diffraction patterns indicated polycrystalline SBT phase. The remanent polarization (Pr) and coercive field (Ec) of SBT film annealed at 75$0^{\circ}C$ were 4.7$\mu$C/$\textrm{cm}^2$ and 115.7kV/cm at an applied voltage of 5V, respectively. The SBT films annealed at 75$0^{\circ}C$ showed practically no polarization fatigue up to 10$^10$ switching cycles.

• 한국재료학회지
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• 제18권10호
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• pp.535-541
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• 2008

Growth behavior of InGaN/GaN self-assembled quantum dots (QDs) was investigated with respect to different growth parameters in low pressure metalorganic chemical vapor deposition. Locally formed examples of three dimensional InGaN islands were confirmed from the surface observation image with increasing indium source ratio and growth time. The InGaN/GaN QDs were formed in Stranski-Krastanow (SK) growth mode by the continuous supply of metalorganic (MO) sources, whereas they were formed in the Volmer-Weber (V-W) growth mode by the periodic interruption of the MO sources. High density InGaN QDs with $1{\sim}2nm$ height and $40{\sim}50nm$ diameter were formed by the S-K growth mode. Dome shape InGaN dots with $200{\sim}400nm$ diameter were formed by the V-W growth mode. InN content in InGaN QDs was estimated to be reduced with the increase of growth temperature. A strong peak between 420-460 nm (2.96-2.70 eV) was observed for the InGaN QDs grown by S-K growth mode in photoluminescence spectrum together with the GaN buffer layer peak at 362.2 nm (3.41 eV).