• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.248-248
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• 2016

We have investigated the crystallinity, preferential ordering, and interfacial stability of 1,4,5,8,9,11-hexaazatriphenylene-hexanitrile (HATCN) thin film interconnected with organic/inorganic multilayer. At the region close to the organic-organic interface, HATCN formed low crystalline order with substantial amorphous phase. As film growth continued, HATCN stacked with high crystalline phase. After a sputtering deposition of the indium zinc oxide (IZO) layer on top of HATCN/organic layer, the volume fraction of preferentially ordered HATCN crystals increased without any structural deterioration. In addition, the HATCN surface was kept quite stable by preserving the sharp interface between HATCN and sputtering deposited IZO layers.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.192.2-192.2
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• 2013

Crystalline order and surface stability of 1,4,5,8,9,11-hexaazatriphenylene-hexanitrile (HATCN) thin films on organic surface were investigated using grazing incidence wide angle x-ray scattering and x-ray reflectivity measurements. In the initial growth regime (less than 20 nm), HATCN molecules were stacked to low crystalline order with substantial amorphous phase. Meanwhile, a thicker film with 50 nm thickness showed high crystalline order of hexagonal phase with three different orientational domains. The domain distribution was quantitatively obtained as a function of tilted angle. By an organic-inorganic interface formation of IZO/HATCN thin film from an indium zinc oxide (IZO) electrode deposition, the surface stability of HATCN film was investigated and the sharp interface was confirmed by the x-ray reflectivity measurement.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.141.1-141.1
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• 2016

저분자 유기태양전지에 사용되는 zinc phthalocyanine(ZnPc)기반의 유기 2층 박막 구조인 ZnPc/C60와 ZnPc/C70에서, 열처리 온도에 따른 유기물층 계면의 변화, ZnPc 층의 격자상수와 응력 변화를 x-ray reflectivity와 GIWAXS 측정을 이용하여 연구하였다. C60 fullerene 층이 있는 ZnPc의 계면은 열처리 온도가 증가하면서 계면의 거칠기가 증가하였으나, C70 fullerene 층이 있을 때는 180도의 고온에서도 계면 거칠기가 증가하지 않고 안정한 상태를 유지하였다. Fullerene층이 있는 ZnPc는 단일 ZnPc 박막에 비해 압축 응력(compressive strain)을 더 받게 되나, 박막의 열처리 온도가 증가함에 따라 응력이 점진적으로 감소하게 된다. 특히 C70 fullerene 층이 있는 경우 ZnPc의 경우 180도에서 응력이 모두 사라진다. 이러한 fullerene 종류에 따른 박막의 응력과 계면의 안정성 특성은 표면 모폴로지에 영향을 주게 되어, ZnPC/C60 박막의 경우 ZnPc/C70에 비해 약 2배 큰 120nm의 grain을 갖게 된다.

• Textile Coloration and Finishing
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• v.26 no.4
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• pp.347-352
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• 2014

Film thickness dependent nanostructure evolution by a post annealing was investigated in poly (3-hexylthiophene):phenyl-C61-butyric acid methyl ester(P3HT:PCBM) films for organic solar cells which were fabricated by dichlorobenzene(DCB) solvent. In case of a 70nm thin film, the thermal annealing process affected to slight increment of the P3HT crystals in the surface region. On the other hand, large number of small sized P3HT crystals near the surface region was formed in the 200nm thick film. The solar cell devices showed the 3% power conversion efficiency(PCE) in 1:0.65 and 1:1 ratio(by weight) of P3HT and PCBM in 70nm and 200nm thickness conditions, respectively. Despite to the similar PCE, the short circuit current Jsc was different in 70nm and 200nm devices, which was related to the different nanostructure of P3HT:PCBM after thermal annealing.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.154-155
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• 2012

The promise of nano-crystalites (nc) as a technological material, for applications including display backplane, and solar cells, may ultimately depend on tailoring their behavior through doping and crystallinity. Impurities can strongly modify electronic and optical properties of bulk and nc semiconductors. Highly doped dopant also effect structural properties (both grain size, crystal fraction) of nc-Si thin film. As discussed in several literatures, P atoms or radicals have the tendency to reside on the surface of nc. The P-radical segregation on the nano-grain surfaces that called self-purification may reduce the possibility of new nucleation because of the five-coordination of P. In addition, the P doping levels of ${\sim}2{\times}10^{21}\;at/cm^3$ is the solubility limitation of P in Si; the solubility of nc thin film should be smaller. Therefore, the non-activated P tends to segregate on the grain boundaries and the surface of nc. These mechanisms could prevent new nucleation on the existing grain surface. Therefore, most researches shown that highly doped nc-thin film by using conventional PECVD deposition system tended to have low crystallinity, where the formation energy of nucleation should be higher than the nc surface in the intrinsic materials. If the deposition technology that can make highly doped and simultaneously highly crystallized nc at low temperature, it can lead processes of next generation flexible devices. Recently, we are developing a novel CVD technology with a neutral particle beam (NPB) source, named as neutral beam assisted CVD (NBaCVD), which controls the energy of incident neutral particles in the range of 1~300eV in order to enhance the atomic activation and crystalline of thin films at low temperatures. During the formation of the nc-/pm-Si thin films by the NBaCVD with various process conditions, NPB energy directly controlled by the reflector bias and effectively increased crystal fraction (~80%) by uniformly distributed nc grains with 3~10 nm size. In the case of phosphorous doped Si thin films, the doping efficiency also increased as increasing the reflector bias (i.e. increasing NPB energy). At 330V of reflector bias, activation energy of the doped nc-Si thin film reduced as low as 0.001 eV. This means dopants are fully occupied as substitutional site, even though the Si thin film has nano-sized grain structure. And activated dopant concentration is recorded as high as up to 1020 #/$cm^3$ at very low process temperature (＜ $80^{\circ}C$) process without any post annealing. Theoretical solubility for the higher dopant concentration in Si thin film for order of 1020 #/$cm^3$ can be done only high temperature process or post annealing over $650^{\circ}C$. In general, as decreasing the grain size, the dopant binding energy increases as ratio of 1 of diameter of grain and the dopant hardly be activated. The highly doped nc-Si thin film by low-temperature NBaCVD process had smaller average grain size under 10 nm (measured by GIWAXS, GISAXS and TEM analysis), but achieved very higher activation of phosphorous dopant; NB energy sufficiently transports its energy to doping and crystallization even though without supplying additional thermal energy. TEM image shows that incubation layer does not formed between nc-Si film and SiO2 under later and highly crystallized nc-Si film is constructed with uniformly distributed nano-grains in polymorphous tissues. The nucleation should be start at the first layer on the SiO2 later, but it hardly growth to be cone-shaped micro-size grains. The nc-grain evenly embedded pm-Si thin film can be formatted by competition of the nucleation and the crystal growing, which depend on the NPB energies. In the evaluation of the light soaking degradation of photoconductivity, while conventional intrinsic and n-type doped a-Si thin films appeared typical degradation of photoconductivity, all of the nc-Si thin films processed by the NBaCVD show only a few % of degradation of it. From FTIR and RAMAN spectra, the energetic hydrogen NB atoms passivate nano-grain boundaries during the NBaCVD process because of the high diffusivity and chemical potential of hydrogen atoms.