• Laser Solutions
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• v.6 no.2
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• pp.9-17
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• 2003

Due to the heat confinement in the shallow region of the target for a short time scale, pulsed laser annealing has received an increasing interest for the fabrication of poly-Si thin film transistors(TFTs) on glass as a low cost substrate in the flat panel displays. The formation and growth mechanisms of poly silicon(poly-Si) grains in thin films are investigated using an excimer laser crystallization system. To understand the crystallization mechanism, the grain formations are observed by FESEM photography. The optical reflectance and transmittance during the crystallization process are measured using HeNe laser optics. A two-step ELC(Excimer Laser Crystallization) process is applied to enhance the grain formation uniformity.

• Macromolecular Research
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• v.14 no.1
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• pp.45-51
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• 2006

We conducted simultaneous, small-angle, X-ray scattering/differential scanning calorimetry (SAXS/DSC) and simultaneous, wide-angle, X-ray scattering (WAXS)/DSC measurements for a polymer blend of poly($\varepsilon$-caprolactone)/poly(ethylene glycol)(PCL/PEG). The time-dependent SAXS/DSC and WAXS/DSC results, measured while the system was quenched below the melting temperature of PCL from a melting state, revealed the competitive behavior between liquid-liquid phase separation and crystallization in the polymer blend. The time-dependent structural evolution extracted from the SAXS/WAXS/DSC results can be characterized by the following four stages in the PCL crystallization process: the induction (I), nucleation (II), growth (III), and late (IV) stages. The influence of the liquid-liquid phase separation on the crystallization of PCL was also observed by phase-contrast microscope and polarized microscope with 1/4$\lambda$ compensator.

• Composites Research
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• v.22 no.3
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• pp.18-28
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• 2009

Blends of poly(lactic acid) (PLA) and poly(butylene terephthalate) (PBT) were prepared by reaction extrusion with para-phenylene diisocyanate (PPDI). The crystallization behavior and biodegradability were investigated by using a differential scanning calorimeter (DSC), a wide angle X-ray diffractometer (WAXD), a contact angle goniometer, and a buffer solution containing esterase. The addition of PBT into PLA polymer matrix induced the cold crystallization of PLA phase, and the crystallization rate of PLA phase was significantly accelerated when both PBT and PPDI participated in the reaction with PLA simultaneously. But the chain extension caused by PPDI decreased the crystallinity and hydrophilicity of PLA and PBT phases. The crystallinity and hydrophilicity did not affect the biodegradability of PLA/PBT blends. However, phase separation between PLA and PBT in PLA/PBT blends increased the interfacial area exposed to the hydrolysis of enzyme, resulting in the improved degradability rate of PLA phase. In contrast, the improved interfacial adhesion between PLA and PBT matrices by the reaction with PPDI reduced the area exposed to the enzyme to decrease the degradation rate of PLA phase.

• Polymer(Korea)
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• v.29 no.2
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• pp.140-145
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• 2005

Effects of the polyol type and the hard segment content of thermoplastic polyurethane (TPU) on the crystallization of hard segments in TPUs were studied employing differential scanning calorimetry. Diols used for the preparation of TPUs were poly(tetramethylene ether glycol) (PTMEG), poly(propylene glycol) (PPG), polycaprolactone (PCL), poly(butylene adipate) (PBA) the molecular weights of which were 2000 and the hard segments contents of TPUs were $35\~44\;wt\%$. We found that crystallization of hard segments in TPUs were observed at higher temperatures and became faster with increasing hard segment contents of TPUs. The crystallization rate of TPU was also affected by the types of polyols used for the preparation of TPUs. It is postulated that lower miscibility of soft segments and hard segments results in higher crystallization rate and increase of cooling crystallization temperatures due to better hydrogen bending between hard segments in melts.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.356-356
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• 2013

Monolithic 3D-IC는 현대 집적회로에서 interconnect로 인해 발생되는 여러 문제들을 해결하기 위해 새롭게 제시되고 있는 기술적 개념으로 구현 시 하위 소자 및 interconnet들에 영향을 주지 않는 저온공정이 필수적이다. 특히 germanium (Ge)은 낮은 녹는점 및 높은 캐리어 이동도 덕분에 3D-IC 구현 시 상위 소자의 channel 물질에 적합한 것으로 알려져 있다. 최근 이러한 Ge을 결정화하기 위해 solid phase crystallization (SPC), metal induced crystallization (MIC), laser annealing과 같은 결정화 방법들이 보고되고 있다. 현재까지 SPC 방법에 의해 얻어진 poly-Ge의 도핑농도 및 이동도와 같은 전기적 특성에 대한 분석은 수행된 바 있으나 3D-IC 공정에 적용이 가능한 MIC 기술을 통해 얻어진 poly Ge 필름에 대한 전기적 특성분석은 부족한 상황이다. 본 연구는 SPC 뿐만 아니라 MIC 방법을 통해 ${\alpha}$-Ge를 결정화시키고 얻어진 poly-Ge 필름의 전기적 특성을 XRD 및 hall effect measurement를 통해 분석하였다. 특히 일반적으로 Ge 내에서 p-type dopant로 동작을 하는 defect과 n-type dopant인 phosphorus 관계를 고려하여 여러 온도에서 SPC 및 MIC에 의해 얻어진 phosphorus doped poly-Ge 필름들의 전기적 특성을 분석하였다.

• Polymer(Korea)
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• v.28 no.6
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• pp.509-518
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• 2004

Microdomain structures and crystallization behavior of the binary blends consisting of an asymmetric block copolymer and a homopolymer were investigated using small-angle X-ray scattering (SAXS), optical micro scope (OM) and differential scanning calorimetry (DSC). Poly(methyl methacrylate)-block-polystyrene block copolymer (PMMA-b-PS) (weight fraction of PMMA =0.53) was mixed with low molecular weight poly(vinylidene fluoride) (PVDF). As the PVDF concentration was increased, the morphological change from a lamellar to a cylindrical structure occurred. The crystallization of PVDF significantly disturbed the orientation of the pre-existing microdomain structure, resulting in a poorly ordered morphology. In the blends, PVDF exhibited unique crystallization behavior due to the PMMA block which is preferentially miscible to PVDF and the space constraint imposed by the microdomains.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.459-462
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• 2000

A new method for the fabrication of poly-Si films is reported using by alternating magnetic flux crystallization (AMFC) of LPCVD a-Si films. In this work we have studied the crystallization of LPCVD a-Si films by alternating magnetic flux. A-Si films were 1200$\AA$-thick deposited at 48$0^{\circ}C$ at a total pressure of 0.25Torr using Si$_2$H$_{6}$/H$_2$. After this step, these a-Si films were thermally annealed by Alternating Magnetic Flux at 43$0^{\circ}C$ for 1hours. The annealed films were characterized using X-ray diffraction (XRD), Raman Spectra, Atomic Force Microscopy(AFM). Both alternating magnetic flux crystallization and solid phase crystallization were investigated to compare enhanced crystallization a-Si. We have found that the low temperature crystallization method at 43$0^{\circ}C$ by alternating magnetic flux.x.

• Polymer(Korea)
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• v.27 no.4
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• pp.285-292
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• 2003

The compatibility of poly(lactic acid)/poly($\varepsilon$-caprolactone) (PLA/PCL) blends as a function of blend composition was studied and triphenyl phosphite (TPP) was applied to PLA/PCL blends as a reactive compatibilizer. Especially the effect of compatibility on the crystallization behavior in both PLA/PCL blends and PLA/PCL blends with TPP was considered. PLA/PCL blends were immiscible based on thermal characteristics of PLA/PCL blends and the miscibility was depend upon the blend composition. The enhancement of compatibility was found in PLA/PCL blends with TPP depend upon its content. The rate of crystallization in PLA/PCL blend varied with blend composition. This was understood as the development of nucleation at the interface of PLA-PCL due to the immiscibility. TPP was acting as a compatibilizer as well as an agent for the acceleration of spherulite growth In PLA. As a result, the crystallization rate increased and the size of spherulite became larger than that of PLA/PCL blend without TPP.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.158-158
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• 2006

The correlation between liquid-liquid phase separation (LLPS) and crystallization at several compositions in statistical copolymer blends of poly (ethylene-co-hexene) (PEH) and poly (ethylene-co-butene) (PEB) has been examined. In this case, the LLPS is coupled with the other ordering process, i.e. crystallization. The overwhelming change in the crystallization kinetics due to the composition fluctuation caused by the spontaneous spinodal LLPS is observed. This coupling mechanism suggests a new mechanism in the nucleation-crystallization process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.36-39
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• 2002

Polycrystalline silicon (poly-Si) thin film transistor (TFT) technology is emerging as a key technology for active matrix liquid crystal displays (AMLCD), allowing the integration of both active matrix and driving circuit on the same substrate (normally glass). As high temperature process is not used for glass substrate because of the low softening points below 450$^{\circ}C$. However, high temperature process is required for getting high crystallization volume fraction (i.e. crystallinity). A poly-Si thin film transistor has been fabricated to investigate the effect of high temperature process on the molybdenum (Mo) substrate. Improve of the crystallinity over 75% has been noticed. The properties of structural and electrical at high temperature poly-Si thin film transistor on Mo substrate have been also analyzed using a sputtering method