• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.481-484
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• 2003

In this study, we fabricated the master metallic nano-stamper with nano pillar patterns to apply replication processes which is adequate for mass production. Master nano patterns with various hole diameters between 300 nm and 1000 nm was fabricated by e-beam lithography. After the seed layer was deposited on the master nano patterns using e-beam evaporation, the nickel was electroformed. In each step, the shape and surface roughness of their patterns were analyzed using SEM and AFM.

• Journal of Powder Materials
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• v.21 no.4
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• pp.260-265
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• 2014

In this study, in order to increase surface ability of hardness and corrosion of magnesium alloy, anodizing and sealing with nano-diamond powder was conducted. A porous oxide layer on the magnesium alloy was successfully made at $85^{\circ}C$ through anodizing. It was found to be significantly more difficult to make a porous oxide layer in the magnesium alloy compared to an aluminum alloy. The oxide layer made below $73^{\circ}C$ by anodizing had no porous layer. The electrolyte used in this study is DOW 17 solution. The surface morphology of the magnesium oxide layer was investigated by a scanning electron microscope. The pores made by anodizing were sealed by water and aqueous nano-diamond powder respectively. The hardness and corrosion resistance of the magnesium alloy was increased by the anodizing and sealing treatment with nano-diamond powder.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.359-361
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• 2003

Nano-porous alumina was investigated as a protecting layer in an AC Plasma Display Panel. A 2 ${\mu}m$ thick nano-porous $Al_2O_3$ layer inserted with MgO was formed on the dielectric layer instead of the conventional 500 nm-thick MgO thin film. Both nano-porous $Al_2O_3$layer and inserted MgO were prepared by wet process. The luminance and luminous efficiency of 3-inch test panel adopting nano-porous $Al_2O_3$ was higher than that of the conventional PDP.

• Journal of Sensor Science and Technology
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• v.31 no.6
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• pp.366-370
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• 2022

A 12 ㎛ pixel-sized 360 × 240 microbolometer focal plane array (MBFPA) was fabricated using a complementary metaloxide-semiconductor (CMOS)-compatible process. To release the MBFPA membrane, an amorphous carbon layer (ACL) processed at a low temperature (<400 ℃) was deposited as a sacrificial layer. The thermal time constant of the MBFPA was improved by using serpentine legs and controlling the thickness of the SiNx layers at 110, 130, and 150 nm on the membrane, with response times of 6.13, 6.28, and 7.48 msec, respectively. Boron-doped amorphous Si (a-Si), which exhibits a high-temperature coefficient of resistance (TCR) and CMOS compatibility, was deposited on top of the membrane as an IR absorption layer to provide heat energy transformation. The structural stability of the thin SiNx membrane and serpentine legs was observed using field-emission scanning electron microscopy (FE-SEM). The fabrication yield was evaluated by measuring the resistance of a representative pixel in the array, which was in the range of 0.8-1.2 Mohm (as designed). The yields for SiNx thicknesses of SiNx at 110, 130, and 150 nm were 75, 86, and 86%, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.318-318
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• 2012

A graphene layer is most important materials in resent year to enhance the electrical properties of semiconductor device due to high mobility, flexibility, strong mechanical resistance and transparency[1,2]. The resistance switching memory with the graphene layer have been reported for next generation nonvolatile memory device[3,4]. Also, the graphene layer is able to improve the electrical properties of memory device because of the high mobility and current density. In this study, the resistance switching memory device with metal-oxide nano-particles embedded in polyimide layer on the graphene mono-layer were fabricated. At first, the graphene layer was deposited $SiO_2$/Si substrate by using chemical vapor deposition. Then, a biphenyl-tetracarboxylic dianhydride-phenylene diamine poly-amic-acid was spin coated on the deposited metal layer on the graphene mono-layer. Then the samples were cured at $400^{\circ}C$ for 1 hour in $N_2$ atmosphere after drying at $135^{\circ}C$ for 30 min through rapid thermal annealing. The deposition of aluminum layer with thickness of 200 nm was done by a thermal evaporator. The electrical properties of device were measured at room temperature using an HP4156a precision semiconductor parameter analyzer and an Agilent 81101A pulse generator. We will discuss the switching mechanism of memory device with metal-oxide nano-particles on the graphene mono-layer.

• Journal of Magnetics
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• v.10 no.2
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• pp.48-51
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• 2005

The spin transfer induced magnetization switching has been reported to occur in magnetic multilayer structures whose scope usually consists of one stack of ferromagnetic / non-ferromagnetic / ferromagnetic (F / N / F) materials. In this work, it is shown that: 1) Copper used as a buffer layer between the free Co and the Au cap-layer can clearly increase the probability to get the spin transfer induced magnetization switching in a simple spin valve Co 11 / Cu 6/ Co 2 (nm); 2) Furthermore, when Ruthenium is simultaneously applied as a buffer layer on the Si-substrate, the critical switching currents can be reduced by $30\%$, and the absolute resistance change delta R $[{\Delta}R]$ of that stack can be enlarged by $35\%$. The enhancement of the spin transfer induced magnetization switching can be ascribed to a lower local stress in the thin Co layer caused by a better lattice match between Co and Cu and the smoothening effect of Ru on the thick Co layer.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.439-440
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• 2002

Nano-Crystalline $CeO_2$ particles were dispersed in deionized water with controlled slurry chemicals for CMP test. According to the CMP test, the removal rate of $SiO_2$ layer was mainly controlled by the size and crystallinity of $CeO_2$ particles which can be controlled by the heat-treatment condition during $CeO_2$ synthesis. In contrast, the removal rate of $Si_3N_4$ layer was significantly influenced by the passivation reagent which protects the $Si_3N_4$ surface layer from excessive dissolution during CMP.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.10 s.175
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• pp.186-194
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• 2005

This study was designed to investigate the mechanical properties of the coating layer on electronic galvanized sheet steel as a part of the ongoing research on the coated steel. Those properties were determined using nano-indentation, the finite element method, and artificial neural networks. First and foremost, the load-displacement curve (the loading-unloading curve) of coatings was derived from a nano-indentation test by CSM (continuous stiffness measurement) and was used to measure the elastic modulus and hardness of the coating layer. The properties derived were applied in FE simulations of a nano-indentation test, and the analytical results were compared with the experimental result. A numerical model for FE simulations was established for the coating layer and the substrate separately. Finally, to determine the mechanical properties of the coating, such as the stress-strain curve, functional equations of loading and unloading curves were introduced and computed using the neural networks method. The results show errors within $5\%$ in comparison with the load-displacement measured by a nano-indentation test.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.252-252
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• 2012

It is widely accepted that short exciton diffusion lengths of organic semiconductors with respect to the film thickness limit the charge (hole and electron) separation before excitons recombination in organic photovoltaic (OPV) cells. Therefore the efficient absorption of incident light within the thin active organic layer is of great importance to improve the power conversion efficiency (PCE) of the cells. In this work, we fabricated 2-dimensionally (2D) nano-patterned poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOST:PSS) layers using capillary phenomenon and nano-imprinting technology at the scale of several hundred nanometers. This 2D nano-patterned PEDOT:PSS layer exerted photonic crystal effect such as redirection of light paths and variation of light intensity at specified wavelengths. It is also expected that the consequently alternated light pass lengths and intensities change the absorption properties of zinc phthalocyanine (ZnPc) thin films grown on top of the nano-patterned PEDOT:PSS layer. The influence of conductivity and thickness of the PEDOT:PSS layer on the absorption properties of ZnPc thin films were also investigated.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.413-413
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• 2012

Lead sulfide (PbS) Colloidal quantum dots (CQDs) are promising material for the photovoltaic device due to its various outstanding properties such as tunable band-gap, solution processability, and infrared absorption. More importantly, PbS CQDs have large exciton Bohr radius of 20 nm due to the uniquely large dielectric constants that result in the strong quantum confinement. To exploit desirable properties in photovoltaic device, it is essential to fabricate a device exhibiting stable performance. Unfortunately, the performance of PbS NQDs based Schottky solar cell is considerably degraded according to the exposure in the air. The air-exposed degradation originates on the oxidation of interface between PbS NQDS layer and metal electrode. Therefore, it is necessary to enhance the stability of Schottky junction device by inserting a passivation layer. We investigate the effect of insertion of passivation layer on the performance of Schottky junction solar cells using PbS NQDs with band-gap of 1.3 eV. Schottky solar cell is the simple photovoltaic device with junction between semiconducting layer and metal electrode which a significant built-in-potential is established due to the workfunction difference between two materials. Although the device without passivation layer significantly degraded in several hours, considerable enhancement of stability can be obtained by inserting the very thin LiF layer (<1 nm) as a passivation layer. In this study, LiF layer is inserted between PbS NQDs layer and metal as an interface passivation layer. From the results, we can conclude that employment of very thin LiF layer is effective to enhance the stability of Schottky junction solar cells. We believe that this passivation layer is applicable not only to the PbS NQDs based solar cell, but also the various NQDs materials in order to enhance the stability of the device.