• 폴리머
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• 제31권5호
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• pp.385-392
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• 2007

Poly (N-vinylpyrrolidone) (PVP) groups were grafted onto a poly(3-hydroxybutyrate-co-3-hydroryvalerate) (PHBV) backbone in order to modify its properties and synthesize a novel biocompatible copolymer. The crystallization behavior of PHBV and grafted PHBV was investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). During the cooling-induced crystallization process, the crystallization temperature and the crystallization rate of the grafted PHBV decreased with increasing PVP weight fraction. On the heating scans of all grafted PHBV samples, a new crystallization exothermic peak appeared at almost the same temperature, suggesting the operation of a recrystallization process, while the melting temperature ($T_m$) and the apparent enthalpy of fusion (${\Delta}H_f$) were not affected by graft modification. During the isothermal crystallization process at the same temperature, the presence of side PVP groups decreased the spherulitic growth rate and the spherulitic band spacing with increasing PVP weight fraction in samples.

• 한국재료학회지
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• 제1권3호
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• pp.151-155
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• 1991

시차주사 열분석기를 이용하여 poly(ethylene oxide)(PEO)/poty(styrene-co-acrylic acid) (SAA) blonds에 대한 등온 결정화 속도를 blend의 조성, 사용한 SAA의 공중합조성 및 결정화 온도에 따라 조사하였다. 실험결과는 Avrami 방정식을 이용하여 분석하였다. Avrami지수는 결정화 온도에 관계없이 거의 모든 blend 시료에서 2의 값을 나타내었다. 결정화 속도는 blend시료의 SAA 함량 및 사용한 SAA 공중합체의 아크릴산함량이 증가함에 따라 급격히 느려졌다.

• Macromolecular Research
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• 제17권10호
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• pp.757-762
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• 2009

The micro domain structures and crystallization behavior of the binary blends of poly(methyl methacrylate)-b-poly(pentafluorostyrene)-b-poly(methyl methacrylate) (PMMA-PPFS-PMMA) triblock copolymer with a low molecular weight poly(vinylidene fluoride) (PVDF) were investigated by small-angle X-ray scattering (SAXS), small-angle light scattering (SALS), transmission electron microscopy (TEM), optical microscopy, and differential scanning calorimetry (DSC). A symmetric, PMMA-PPFS-PMMA triblock copolymer with a PPFS weight fraction of 33% was blended with PVDF in N,N-dimethylacetamide (DMAc). In the wide range of PVDF concentration between 10.0 and 30.0 wt%, PVDF was completely incorporated within the PMMA micro domains of PMMA-PPFS-PMMA without further phase separation on a micrometer scale. The addition of PVDF altered the phase morphology of PMMA-PPFS-PMMA from well-defined lamellar to disordered. The crystallization of PVDF significantly disturbed the domain structure of PMMA-PPFS-PMMA in the blends, resulting in a poorly-ordered morphology. PVDF displayed unique crystallization behavior as a result of the space constraints imposed by the domain structure of PMMA-PPFS-PMMA. The pre-existing microdomain structures restricted the lamellar orientation and favored a random arrangement of lamellar crystallites.

• 대한화학회지
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• 제32권3호
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• pp.276-284
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• 1988

1,3-propane diol, 1,5-pentane diol, 1,6-hexane diol, 분자량이 300인 poly(ethylene glycol)등을 제 3의 디올로 사용하여 poly(ethylene terephthalate)를 개질하여 개질된 copolyester의 결정화 거동을 비교하였다. 개질된 copolyester 중 제 3의 디올 함량이 약 4몰%인 경우 유리전이온도 부근에서 승온시키면서 유리전이온도로 부터 일정 온도 위에서의 결정화 속도를 비교하거나, 녹는점 부근에서 등온 결정화시켜 동일 과냉각 상태에서의 결정화 속도를 비교하면 가해진 디올의 길이가 짧을수록 결정화 속도가 크게 촉진되었다. 이에 반해 녹는점 부근에서 강온시키면서 동일 과냉각 상태에서의 결정화 속도를 비교하면 가해진 디올의 길이가 길수록 결정화 속도가 크게 촉진되었다.

• 한국표면공학회지
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• 제47권1호
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• pp.20-24
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• 2014

Joule heat is generated by applying an electric filed to a conductive layer located beneath or above the amorphous silicon film, and is used to raise the temperature of the silicon film to crystallization temperature. An electric field was applied to an indium tin oxide (ITO) conductive layer to induce Joule heating in order to carry out the crystallization of amorphous silicon. Polycrystalline silicon was produced within the range of a millisecond. To investigate the kinetics of Joule-heating induced crystallization (JIC) solid phase crystallization was conducted using amorphous silicon films deposited by plasma enhanced chemical vapor deposition and using tube furnace in nitrogen ambient. Microscopic and macroscopic uniformity of crystallinity of JIC poly-Si was measured to have better uniformity compared to that of poly-Si produced by other methods such as metal induced crystallization and Excimer laser crystallization.

• 전자공학회논문지D
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• 제34D권4호
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• pp.33-39
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• 1997

The crystallization temperature of an amorphous silicon (a-Si) can be lowered down to 400.deg. C by a new method : Double-metal induced lateral crystallization (DMILC). The a-Si film was laterally crystallized from Ni and Pd deposited area, and its lateral crystallization rate reaches up to 0.2.mu.m/hour at that temperature and depends on the overlap length of Ni and Pd films; the shorter the overlap length, the faster the rate. Poly-Silicon thin film transistors (poly-Si TFT's) fabricated by DMILC at 400.deg. C show a field effect mobility of 38.5cm$^{3}$/Vs, a minimum leakage current of 1pA/.mu.m, and a slope of 1.4V/dec. The overlap length does not affect the characteristics of the poly-Si TFT's, but determines the lateral crystallization rate.

• 한국전기전자재료학회논문지
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• 제21권1호
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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.

• 한국재료학회지
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• 제24권9호
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• pp.443-450
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• 2014

Amorphous (a-Si) films were epitaxially crystallized on a very thin large-grained poly-Si seed layer by a silicide-enhanced rapid thermal annealing (SERTA) process. The poly-Si seed layer contained a small amount of nickel silicide which can enhance crystallization of the upper layer of the a-Si film at lower temperature. A 5-nm thick poly-Si seed layer was then prepared by the crystallization of an a-Si film using the vapor-induced crystallization process in a $NiCl_2$ environment. After removing surface oxide on the seed layer, a 45-nm thick a-Si film was deposited on the poly-Si seed layer by hot-wire chemical vapor deposition at $200^{\circ}C$. The epitaxial crystallization of the top a-Si layer was performed by the rapid thermal annealing (RTA) process at $730^{\circ}C$ for 5 min in Ar as an ambient atmosphere. Considering the needle-like grains as well as the crystallization temperature of the top layer as produced by the SERTA process, it was thought that the top a-Si layer was epitaxially crystallized with the help of $NiSi_2$ precipitates that originated from the poly-Si seed layer. The crystallinity of the SERTA processed poly-Si thin films was better than the other crystallization process, due to the high-temperature RTA process. The Ni concentration in the poly-Si film fabricated by the SERTA process was reduced to $1{\times}10^{18}cm^{-3}$. The maximum field-effect mobility and substrate swing of the p-channel poly-Si thin-film transistors (TFTs) using the poly-Si film prepared by the SERTA process were $85cm^2/V{\cdot}s$ and 1.23 V/decade at $V_{ds}=-3V$, respectively. The off current was little increased under reverse bias from $1.0{\times}10^{-11}$ A. Our results showed that the SERTA process is a promising technology for high quality poly-Si film, which enables the fabrication of high mobility TFTs. In addition, it is expected that poly-Si TFTs with low leakage current can be fabricated with more precise experiments.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.58.1-58.1
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• 2010

We have developed a novel crystallization process, where the crystallization temperature is lowered compared to the conventional RTA process and the metal contamination is lowered compared to the conventional VIC process. A very-thin a-Si film was deposited and crystallized at $550^{\circ}C$ for 3 h by the VIC process and then a thick a-Si film was deposited and crystallized by the RTA process at $680^{\circ}C$ for 5 min using the VIC poly-Si layer as a crystallization seed layer. The RTA crystallized temperature could be lowered up to $50^{\circ}C$, compared to RTA process alone. The poly-Si film appeared a needle-like growth front and relatively well-arranged (111) orientation. In addition, the Ni concentration in the poly-Si film was lowered to $3{\times}10^{17}\;cm^{-3}$ and that at the poly-Si/$SiO_2$ interface was lowered to $5{\times}10^{19}\;cm^{-3}$. The reduction in metal contamination could be greatly helpful to achieve a low leakage current in poly-Si TFT, which is the critical parameter for commercialization of AMOLED.

• 한국진공학회지
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• 제12권2호
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• pp.130-135
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• 2003

최근, poly-Si 박막은 저가의 박막소자응용을 위하여 사용되어 왔다. 그러나, 유리기판 위에서 일반적인 고상결정화(SPC) 방식으로 poly-Si 박막을 얻기는 불가능하다. 이러한 단점 때문에 유리와 같은 저가기판 위에 poly-Si을 결정화하는 연구가 최근 다양하게 진행되고 있다. 본 논문에서는 급속열처리(RTA)를 이용하여 유연한 기판인 몰리브덴 기판 위에서 a-Si:H를 성장시킨 후 고온결정화에 대한 연구를 진행하였다 고온결정화된 poly-Si 박막은 150$\mu\textrm{m}$ 두께의 몰리브덴 기판 위에 성장되었으며 결정화 온도는 고 진공하에서 $750^{\circ}C$~$1050^{\circ}C$ 사이에서 결정화된 시료에 대하여 결정화도, 결정화 면방향, 표면구조 및 전기적 특성이 조사되었다. 결정화온도 $1050^{\circ}C$에서 3분간 결정화된 시료의 결정화도는 92%를 나타내고 있었다. 결정화된 poly-Si 박막으로 제작된 TFT 소자로부터 전계효과 이동도 67 $\textrm{cm}^2$/Vs을 얻을 수 있었다.