• Korean Journal of Materials Research
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• v.16 no.6
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• pp.394-399
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• 2006

Ferroelectric $HoMnO_3$ thin films were deposited on the Si(100) substrate at $700^{\circ}C$ for 2 hrs by metalorganic chemical vapor deposition (MOCVD) and post-annealed at 850oC by rapid thermal process (RTP). Electrical properties and crystalline phases of $HoMnO_3$ thin films were investigated as a function of postannealing time. Single phase of hexagonal symmetry with c-axis preferred orientation was obtained from $HoMnO_3$ thin films post-annealed at $850^{\circ}C$ for 5 min, while the c-axis preferred orientation was decreased with the increase of post-annealing time, and the thin films post-annealed at $850^{\circ}C$ for 15 min showed the mixture phases of hexagonal and orthorhombic symmetry. P-E (Polarization-Electric field) hysteresis loop of ferroelectric $HoMnO_3$ thin films was observed only for the single phase of hexagonal symmetry, but that was not observed for the mixture phases of the hexagonal and orthorhombic symmetry, which was discussed with the bond valence of Mn ion of crystalline phase. Leakage current density was dependent on the microstructure of thin films as well as the change of valence of Mn ion.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.3
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• pp.299-302
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• 1999

$La_{2-x}Sr_{x}CuO_{4}$ single-crystalline films were prepared on bulk single crystals of Zn-doped $La_{2-x}Sr_{x}CuO_{4}$ as the substrates by LPE technique using two deferent methods. When prepared using an alumina crucible in normal electrical furnace, the $La_{2-x}Sr_{x}CuO_{4}$ films were contaminated with less than 3 at% aluminum from the alumina crucibles. Aluminum contamination either reduced or completely destroyed the superconductivity of the $La_{2-x}Sr_{x}CuO_{4}$ films, For LPE growth by modified TSFZ method using an infrared heating furnace without crucibles, the $La_{2-x}Sr_{x}CuO_{4}$ films of x=0.11 showed superconducting with $Tc_{onset}=36\;K$, which is 10 K higher than that in the $La_{2-x}Sr_{x}CuO_{4}$ bulk single crystals.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.3
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• pp.15-19
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• 2002

It is a quite quality concerming to the temperature of single cystalline growth as it does when we get most of heat treating products. It is also important factor to control the temperature when we make the A1203(single crystalline) used to artificial jewels, glass af watches, and heat resistant transparent glasses. Thus, it is a major interest to get the proper temperature in accordance with the time process while we are making mixture of oxygen and hydrogen to have the right tempearture. In this paper, we will study of electrical valve positioning system with DC-Motor for the gas mixture to improve the quality of products.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.7
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• pp.375-379
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• 2015

A proper estimate of solar cell efficiency is of great importance for the feasibility analysis of solar cell power plant development. Since solar cell efficiency depends on temperature, several methods have been introduced to measure it by operating temperature modulation. However, the methods either rely on the external environment or need expensive equipment. In this paper, a thermoelectric module was used to control the operating temperature of crystalline silicon solar cells effectively and precisely over a wide range. The output characteristics of crystalline silicon solar cells in response to operating temperatures from $-5^{\circ}C$ to $100^{\circ}C$ were investigated experimentally. Their efficiencies decreased as the temperature rose, since the decrease in the open circuit voltage and fill factor exceeded the increase in the short circuit current. The maximum power temperature coefficient of the single crystalline solar cell was more sensitive to temperature change than that of the polycrystalline solar cell.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.275-275
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• 2009

CdTe(331)/Si(211) and CdTe(400)/Si(100) thin films have been grown by MOCVD(metal organic chemical vapor deposition) system for large scale of IFPAs(IR focal plane arrays). We have investigated the effect of various growth parameters on the surface morphology and structural quality. Single crystalline CdTe(331) films were grown by two stage growth method - low temperature buffer layer step and high temperature growth step. In other case, single crystal of CdTe(400) films were grown on a few atomic layer thickness of GaAs which is grown on Si(100) substrate by molecular beam epitaxy. The crystalline quality of the films was analyzed by X-ray diffraction. The surface morphology and crystal structure of CdTe films were characterized by optical microscope.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.5
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• pp.215-219
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• 2004

ZnO epitaxial films have been grown on a (0001)sapphire substrate by RF magnetron sputtering. The single crystalline ZnO films were grown at the condition of growth rate of about 0.1~0.2 $\mu\textrm{m}$/hr and the substrate temperature of $600^{\circ}C$. The film thickness was about 400~500 nm. The thin film quality and micro-structure have been evaluated by XRD and TEM observation.

• Journal of the Korean Ceramic Society
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• v.44 no.3 s.298
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• pp.142-146
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• 2007

High-quality one-dimensional GaN nanorods and nanowires were synthesized on Ni-coated c-plan sapphire substrate using halide vapor-phase epitaxy (HVPE). Their structure and optical properties were investigated by X-ray diffraction, scanning and transmission electron microscopy, and photoluminescence techniques. Full substrate coverage of densely packed, uniform, straight and aligned one-dimensional GaN nanowires with a diameter of 80nm were grown at $700{\sim}900^{\circ}C$. The X-ray diffraction patterns, transmission electron microscopic image, and selective area electron diffraction patterns indicate that the one-dimensional GaN nanostructures are a pure single crystalline and preferentially oriented in the [001] direction. We observed high optical quality of GaN nanowires by photoluminescence analysis.

• Journal of the Korean Ceramic Society
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• v.30 no.3
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• pp.236-242
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• 1993

As the fundamental research on preparation of fine single crystalline ferroxaplana by means of glass-crystallization methods using steel twin-roller, the properties of ferroxplana crystallized from glass were studied. Most of the specimens quenched by twin-roller at about 130$0^{\circ}C$ were glass phase, the crystallization of these glasses underwent multi-steps and ferroxplana phase was only stable in the temperature range of 88$0^{\circ}C$ to 95$0^{\circ}C$. Above 95$0^{\circ}C$ ferroxplana begines to be decomposed in glass. Ferroxplana had such magnetic properties as M8=29emu/g, MHC=166Oe, and Curie Temperature, Tc=610$\pm$5K.

• Proceedings of the KAIS Fall Conference
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• 2009.12a
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• pp.633-635
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• 2009

It is a quite quality concerning to control temperature of single crystalline growth as it does when you get most of heat treating products. It is also important factor to control temperature when you make the $Al_2O_3$(single crystalline) used to artificial jewels, glass of watches, heat resistant transparent glasses. Thus, it is a major interest to get the proper temperature in accordance with the time process while you are making mixture of oxygen and hydrogen to have the right temperature. In this paper, we will study of electrical valve positioning system for the gas mixture to improve the quality of products.

• Proceedings of the KAIS Fall Conference
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• 2010.11a
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• pp.337-340
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• 2010

It is a quite quality concerning to control temperature of single crystalline growth as it does when you get most of heat treating products. It is also important factor to control temperature when you make the Al2O3(single crystalline) used to artificial jewels, glass of watches, heat resistant transparent glasses. Thus, it is a major interest to get the proper temperature in accordance with the time process while you are making mixture of oxygen and hydrogen to have the right temperature. In this paper, we will study of electrical valve positioning system for the gas mixture to improve the quality of products.