Search results for: Seok Kyu Han

Items from 1 to 13 out of 13 results

article

Growth and characterization of MgxZn1−xO films grown on r-plane sapphire substrates by plasma-assisted molecular beam epitaxy

Seok Kyu Han, Hyo Sung Lee, Dong-Yeob Kim, Soon-Ku Hong, more

Journal of Alloys and Compounds > 2015 > 623 > C > 1-6

We report on the structural and optical properties of non polar a-plane Mg_xZn₁₋_xO (0⩽x⩽0.57) films on r-plane sapphire substrates grown by plasma-assisted molecular beam epitaxy. Reflection high energy electron diffraction (RHEED) revealed a formation of cubic MgO phase when an Mg concentration increases. Room temperature (RT) photoluminescence (PL) and transmission electron microscopy consistently...

article

Growth and stuctural characterization of InGaN layers with controlled In content prepared by plasma-assisted molecular beam epitaxy

Eun-Jung Shin, Se-Hwan Lim, Myoungho Jeong, Dong Seok Lim, more

Thin Solid Films > 2013 > 546 > Complete > 42-47

InGaN layers with controlled In composition up to 30at.% are grown on c-plane sapphire substrates by plasma-assisted molecular beam epitaxy. By considering the growth rate differences in GaN and InN caused by different vapor pressure and sticking coefficient, factors of the Ga and In source fluxes for the targeted In composition are determined. By applying the factors, InGaN layers with the almost...

article

Suppression of composition modulation in In‐rich In_xGa_1−xN layer with high In content (x ∼ 0.67)

Myoungho Jeong, Hyo Sung Lee, Seok Kyu Han, Eun‐Jung Shin, more

physica status solidi (a) > 208 > 12 > 2737 - 2740

The composition modulation of in In‐rich In_xGa_1−xN layers with an indium content as high as ∼67% was suppressed in plasma‐assisted molecular beam epitaxy on c‐sapphire substrates. It was found that the higher nitrogen plasma flow rate was very effective in suppression of composition modulation in In‐rich InGaN layers. X‐ray diffraction, X‐ray energy dispersive spectroscopy, and transmission electron...

article

Properties of (11–20) a-plane ZnO films on sapphire substrates grown at different temperatures by plasma-assisted molecular beam epitaxy

Seok Kyu Han, Soon-Ku Hong, Jae Wook Lee, Jae Goo Kim, more

Thin Solid Films > 2011 > 519 > 19 > 6394-6398

The effects of growth temperatures (in a wide range from 100 to 800°C) on properties of a-plane (112¯0) ZnO films grown on r-plane (11¯02) sapphire substrates by plasma-assisted molecular beam epitaxy were investigated. The film was grown as polycrystalline at 100°C, but grown as single crystalline at the temperatures from 200 to 800°C without any mixture of c-plane (0001) ZnO and m-plane (101¯0)...

article

Growth and optical properties of ZnO nanorods prepared through hydrothermal growth followed by chemical vapor deposition

Dong-Suk Kang, Hyo Sung Lee, Seok Kyu Han, Vibha Srivastava, more

Journal of Alloys and Compounds > 2011 > 509 > 16 > 5137-5141

We report on the synthesis of high-quality ZnO nanorods by combining hydrothermal growth (HG) and chemical vapor deposition (CVD) processes. Vertically aligned and closely packed ZnO nanorods were grown by HG on a sputtered ZnO seed layer on a SiO ₂ /Si (001) substrate. The top surface of the HG-prepared ZnO nanorods showed very flat surfaces compared with that of the sputtered ZnO seed layer...

article

Effects of low temperature ZnO and MgO buffer thicknesses on properties of ZnO films grown on (0001) Al2O3 substrates by plasma-assisted molecular beam epitaxy

Jae Goo Kim, Seok Kyu Han, Sang Mo Yang, Soon-Ku Hong, more

Thin Solid Films > 2010 > 519 > 1 > 223-227

We investigated the structural properties of Zn-polar ZnO films with low temperature (LT) ZnO and MgO buffer layers grown by plasma-assisted molecular beam epitaxy on (0001) c-Al ₂ O ₃ substrates using X-ray diffraction and transmission electron microscopy (TEM). The effects of MgO buffer layer thickness and LT ZnO buffer layer thickness were also examined. The optimum thicknesses...

article

Investigation of nonpolar (112¯0) a-plane ZnO films grown under various Zn/O ratios by plasma-assisted molecular beam epitaxy

Seok Kyu Han, Jung-Hyun Kim, Soon-Ku Hong, Jae-Ho Song, more

Journal of Crystal Growth > 2010 > 312 > 15 > 2196-2200

Structural and optical properties of nonpolar a-plane ZnO films grown with different II/VI ratios on r-plane sapphire substrates by plasma-assisted molecular beam epitaxy were investigated. Even by increasing the II/VI ratio across the stoichiometric flux condition a consistent surface morphology of striated stripes along the ZnO 〈0001〉 direction without any pit formation was observed, which is contrary...

article

Growth of epitaxial ZnO films on Si (111) substrates with Cr compound buffer layer by plasma-assisted molecular beam epitaxy

Jung-Hyun Kim, Seok Kyu Han, Soon-Ku Hong, Jae Wook Lee, more

Journal of Crystal Growth > 2010 > 312 > 15 > 2190-2195

Single crystalline ZnO film was grown on (111) Si substrate through employing an oxidized CrN buffer layer by plasma-assisted molecular beam epitaxy. Single crystalline characteristics were confirmed from in-situ reflection high energy electron diffraction, X-ray pole figure measurement, and transmission electron diffraction pattern, consistently. Epitaxial relationship between ZnO film and Si substrate...

article

Microstructural investigation of ZnO films grown on (111) Si substrates by plasma-assisted molecular beam epitaxy

Sang Mo Yang, Seok Kyu Han, Jae Wook Lee, Jung-Hyun Kim, more

Journal of Crystal Growth > 2010 > 312 > 9 > 1557-1562

Microstructural analyses of of ZnO films on (111) Si substrates grown by plasma-assited molecualr beam epitaxy were performed in this study. Zn pre-deposition and its subsequent oxidation, in which either oxygen gas or oxygen-plasma was used as the oxygen source, were employed before ZnO growth. Both reflection high energy electron diffraction and x-ray pole figure showed the single crystalline features...

chapter

Growth and optical properties of ZnO nanorods prepared through hydrothermal growth followed by chemical vapor deposition

Seok Kyu Han, Dong-Suk Kang, Soon-Ku Hong, Min-Jung Kim, more

2010 3rd International Nanoelectronics Conference (INEC) > 1098 - 1099

2010 IEEE 3rd International Nanoelectronics Conference (INEC 2010)

Very well aligned vertical ZnO nanorods with high optical quality were successfully synthesized by sequentially employing an aqueous solution method on a ZnO seed layer and a thermal chemical vapor deposition (CVD). The process is growing the upper ZnO nanorods by using CVD on top of the bottom nanorods synthesized by using an aqueous solution method on a Si substrate with a ZnO seed layer. These...

article

Investigation of initial growth and very thin (112¯0) ZnO films by cross-sectional and plan-view transmission electron microscopy

Jae Wook Lee, Seok Kyu Han, Soon-Ku Hong, Jeong Yong Lee

Applied Surface Science > 2010 > 256 > 6 > 1849-1854

Initial growth and very thin a-plane (1 1 2¯ 0) ZnO films grown on r-plane (1 1¯ 0 2) Al ₂ O ₃ substrates by plasma-assisted molecular beam epitaxy (PAMBE) were studied using cross-sectional and plan-view transmission electron microscopy (TEM). The ZnO films were grown via Volmer-Weber growth mode, in which the (1 0 1¯ 0) facets were developed first followed by the (1 1 2¯ 0) facets...

article

Interface and defect structures in ZnO films on m-plane sapphire substrates

Jae Wook Lee, Jung-Hyun Kim, Seok Kyu Han, Soon-Ku Hong, more

Journal of Crystal Growth > 2010 > 312 > 2 > 238-244

Interface and defect structures in ZnO films grown on (101¯0) m-plane sapphire substrates by plasma-assisted molecular beam epitaxy were investigated by transmission electron microscopy (TEM). Distribution of misfit dislocations (MDs) at the ZnO/Al ₂ O ₃ interfaces was orientation dependent and quite anisotropic. In addition, type-І ₁ stacking faults (SFs) bounded by the Frank...

article

Characterization of microstructure and defects in epitaxial ZnO (112¯0) films on Al2O3 (11¯02) substrates by transmission electron microscopy

Jae Wook Lee, Seok Kyu Han, Soon-Ku Hong, Jeong Yong Lee, more

Journal of Crystal Growth > 2008 > 310 > 18 > 4102-4109

Microstructure and defects in nonpolar ZnO (112¯0) films with different thicknesses were studied by transmission electron microscopy. The ZnO films were grown on Al ₂ O ₃ (11¯02) substrates by plasma-assisted molecular beam epitaxy. The misfit dislocations were observed at the interface with regularly spaced configurations, which were well agreed with the equilibrium spacing of the...

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