• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.1
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• pp.1-4
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• 2008

The electrical characteristics of polycrystalline silicon (poly-Si) thin film transistor (TFT) crystallized by excimer laser annealing (ELA) method were evaluated, The polycrystalline silicon thin-film transistor (poly-Si TFT) has higher electric field-effect-mobility and larger drivability than the amorphous silicon TFT. However, to poly-Si TFT's using conventional processes, the temperature must be very high. For this reason, an amorphous silicon film on a buried oxide was crystallized by annealing with a KrF excimer laser (248 nm)to fabricate a poly-Si film at low temperature. Then, High permittivity $HfO_2$ of 20 nm as the gate-insulator was deposited by atomic layer deposition (ALD) to low temperature process. In addition, the solid phase crystallization (SPC) was compared to the ELA method as a crystallization technique of amorphous-silicon film. As a result, the crystallinity and surface roughness of poly-Si crystallized by ELA method was superior to the SPC method. Also, we obtained excellent device characteristics from the Poly-Si TFT fabricated by the ELA crystallization method.

• Journal of Korean Society on Water Environment
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• v.25 no.4
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• pp.515-521
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• 2009

In this study, the applicability of $CaCO_3$ as a seed material for crystallization reaction was tested. $CaCO_3$ was ground to lesser than 425 mesh and was made to media mixed with binder. Batch experiment was to investigate the ${PO_4}^{3-}-P$ removal efficiency of different parameters such as $CaCO_3$ dosage and binder ratio, size, type and mass of media. In addition, the effect of phosphorus removal from wastewater was tested using a lab-scaled crystallization reactor. At the results of the batch test, phosphorus removals were improved with increasing $CaCO_3$ dosage and media mass but were decreased with increasing media size. Moreover, phosphorus removals were influenced by specific surface area but media type. The average T-P and ${PO_4}^{3-}-P$ removal efficiency in a lab-scaled crystallization reactor with $CaCO_3$ media for wastewater were shown to be 60.2% and 60.3% for 18 days of operation time.

• Journal of the Korean Chemical Society
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• v.31 no.6
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• pp.582-589
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• 1987

The thermal properties of poly (ethylene terephthalate) (PET) modified by 5-sulfoisophthalic acid sodium salt(SIAS) were studied. The glass transition temperature was increased, and the melting temperature and the crystallization rate were decreased as the content of SIAS unit was increased. The decrease of crystallization rate is thought to be due to the polar, bulky sulfonic acid sodium salt group which greatly retards the crystallization on to the growing crystal surface of the diffused polymer chain. The crystallization mechanism of copolyester is dependent on the content of SIAS unit and the three dimensional growth of crystal is hindered by the added SIAS unit.

• Journal of the Korean Physical Society
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• v.73 no.11
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• pp.1716-1724
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• 2018

Single crystal of organic lead halide ($CH_3NH_3PbX_3$; $CH_3NH^+_3$ = methylammonium (MA), $X=Cl^-$, $Br^-$, $I^-$) is the best candidate for material intrinsic property studies due to no grain boundary and high crystal quality than the film having a lot of grain boundary and surface defects. The representative crystallization methods are inverse temperature crystallization (ITC) and anti-solvent vapor assisted crystallization (AVC). Herein, we report bandgap modulated organic lead halide single crystals having a bandgap ranging from ~ 2.1 eV to ~ 3 eV with ITC and AVC methods. The bandgap modulation was achieved by controlling the solvents and chloride-to-bromide ratio. Structural, optical and compositional properties of prepared crystals were characterized. The results show that the crystals synthesized by the two crystallization methods have similar properties, but the halide ratios in the crystals synthesized by the AVC method are controlled more quantitatively than the crystals synthesized by ITC.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.89-93
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• 1995

Effects of hydrogenation in amorphous silicon rile growths on Solid Phase Crystallization (SPC) was investigated using x-ray diffractometry, energy dispersive Spectroscopy, and Raman spectrum. Interdiffusion of barium(Ba) and aluminum(Al) compounds of corning substrate was observed in both of rf sputtering and LFCVD films under the low temperature(580$^{\circ}C$) annealing. Low degree of crystallinity resulted from the interdiffusion was obtained. Highly applicable degree of crystallinity was obtained through the mechanical damage induced surface activation on amorphous silicon films. X-ray diffraction intensity of (111) orientation was used to characterize the degree of crystallinity of SPC. Nucleation and growth rate in SPC could be controllable through the employed surface treatment. IIydrogenated LPCVD films showed the superior crystallinity to non-hydrogenated sputtering films. Insignificant effects of activation treatment in sputtered film was of activation treatment in sputtered film was observed on SPC.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.191.1-191.1
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• 2014

Crystallization has become the most popular technique for the separation of enantiomers since the Pasteur's discovery. To investigate mechanism of crystallization of chiral molecules, it is necessary to study self-assembled structures on two-dimensional surface. Here, we have studied two-dimensional self-assembled structures of an unnatural amino acid, (S)-${\beta}$-methyl naphthalen-1-${\gamma}$-aminobutyric acid (${\gamma}^2$-1-naphthylalanine) on Au(111) surface at 150 K using scanning tunneling microscopy (STM). At initial stage, we found two chiral honeycomb structures which are counter-clockwise and clockwise configurations in one domain. The molecules are arranged around molecular vacancies, dark hole. By further increasing the amounts of adsorbed ${\gamma}^2$-1-naphthylalanine, a well-ordered square packed structure was observed. In addition, we found the other structure that molecules were trapped in the pore of the hexagonal molecular assembly.

• Proceedings of the Materials Research Society of Korea Conference
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• 2001.05a
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• pp.41-41
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• 2001

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.08a
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• pp.122.3-122
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• 1998

• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.939-944
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• 1997

The films of zeolite X on the surface of metal sieve were prepared by continuous crystallization method. It is known that the growth of zeolite crystal on the surface of metal is mainly dependent on the surface composition of metal sieve. In the present work, the zeolite nuclei could be easily formed as Cr content on the metal surface was removed by acid treatment. In order to investigate the proedure growing of zeolite crystal by the continuous crystallization method, the composition of zeolite X($6.36Na_2O-Al_2O_3-5.3SiO_2-190.8H_2O$)was supplied every 12hour. Then the mechanism and inter-relationship between the metal surface and nucleation are investigated. The results show that as the content of silica increases in the gel mixture, the nuclei of zeoilite are easily formed on the metal surface. Also, it was confirmed that the particle of zeolite stuck on the metal surface continues the linear growth. The particles are combined by the reaction of polycondensation, and finally become the shape of crystal. The sample synthesized by the film type was confirmed as zeolite X by the analyses of SEM and XRD.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.5
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• pp.33-39
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• 1998

The BST (Ba$_{1-x}$ Sr$_{x}$TiO$_{3}$)(50/50) thin film has been grown by RF magnetron reactive sputtering and its characteristics such as crystallization, surface roughness, and electrical properties have been investigated with varying the film thickness. The crystallization and surface roughness of BST thin film are investigated by using XRD and AFM, respectively The BST thin film anealed at 800.deg. C for 2 min has pure perovskite structure and good surface roughness of 16.1.angs.. We estimate that the thickness and dielectric constant of interface layer between BST film and electrode are 3nm and 18.9, respectively, by measuring the capacitance with various film thickness. As the film thickness increases form 80nm to 240nm, the dielectric constant at 10kHz increases from 199 to 265 and the leakage current density at 200kV/cm decreases from 0.682.mu.A/cm$^{2}$ to 0.181 .mu.A/cm$^{2}$. In the case of 240nm-thick BST thin film, the charge storage density and leakage current density at 5V are 50.5fC/.mu.m$^{2}$ and 0.182.mu.A/cm$^{2}$, respectively. The values indicate that the BST thin film is a very useful dielectric material for the DRAM capacitor.or.