• Transactions of the Society of Information Storage Systems
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• v.9 no.2
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• pp.67-71
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• 2013

The fabrication method of plasmonic nanodots on silicon substrate has been developed to improve the efficiency of thin film solar cells. Nanoscale metallic nanodots arrays are fabricated by anodic aluminum oxide (AAO) template mask which can have different structural parameters by varying anodization conditions. In this paper, the structural parameters of gold nanodots, which can be controlled by the diverse structures of AAO template mask, are investigated to enhance the optical properties of a-Si thin film solar cells. It is found that optical properties of the thin film solar cells are improved by finding optimization values of the structural parameters of the gold nanodot array.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.9-10
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• 2005

We report on the fabrication and characterization of self- and artificially-controlled ZnO nanostructures have been investigated to establish nanostructure blocks for ZnO-based nanoscale device application. Systematic realization of self- and artificially-controlled ZnO nanostructures on $SiO_2/Si$ substrates was proposed and successfully demonstrated utilizing metalorganic chemical vapor deposition (MOCVD) in addition with a focused ion beam (FIB) technique. Widely well-aligned two-dimensional ZnO nanodot arrays ($4{\sim}10^4$ nanodots of 130-nm diameter and 9-nm height over $150{\sim}150{\mu}m^2$ with a period of 750 nm) have been realized by MOCVD on $SiO_2/Si$ substrates patterned by FIB. A low-magnification FIB nanopatterning mode allowed the periodical nanopatterning of the substrates over a large area in a short processing time. Ga atoms incorporated into the surface areas of FIB-patterned nanoholes during FIB engraving were found to play an important role in the artificial control of ZnO, resulting in the production of ZnO nanodot arrays on the FIB-nanopatterned areas. The nanodots evolved into dot clusters and rods with increasing MOCVD growth time.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.1
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• pp.12-19
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• 2006

Metalorganic chemical vapor deposition (MOCYD) techniques have been applied to fabricate semiconducting ZnO thin films and nanostructures, which are promising for novel optoelectronic device applications using their unique multifunctional properties. The growth and characterization of ZnO thin films on Si and $SiO_2$ substrates by MOCYD as fundamental study to realize ZnO nanostructures was carried out. The precise control of initial nucleation processes was found to be a key issue for realizing high quality epitaxial layers on the substrates. In addition, fabrication and characterization of ZnO nanodots with low-dimensional characteristics have been investigated to establish nanostructure blocks for ZnO-based nanoscale device application. Systematic realization of self- and artificially-controlled ZnO nanodots on $SiO_2/Si$ substrates was proposed and successfully demonstrated utilizing MOCYD in addition with a focused ion beam technique.

• Journal of Magnetics
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• v.13 no.2
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• pp.53-56
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• 2008

This study proposes a simple nano-patterning process for the fabrication of magnetic nanodot arrays on a large area substrate. Ni nanodots were fabricated on a large area (4 inches in diameter) Si substrate using the soft lithographic technique using self-assembled surface micelles of Polystyrene-block-Poly(methyl methacrylate) (PS-b-PMMA) diblock copolymer formed at the air/water interface as a mask. The hexagonal array of micelles was successfully transferred to a Ni thin film on a Si substrate using the Langmuir-Blodgett technique. After ion-mill dry etching, a magnetic Ni nanodot array with a regular hexagon array structure was obtained. The Ni nanodot array showed in-plane easy axis magnetization and typical soft magnetic properties.

• Journal of the Korean Magnetics Society
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• v.17 no.3
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• pp.137-140
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• 2007

The ordering of nanopores in AAO has been improved by using laser interference lithography. After growing Fe and Cu on this substrate in vacuum and removing AAO, Fe nanodots are fabricated. The nanopores in AAO and nanodots are ordered in one dimension following the prepatterning. It has been confirmed from the magnetic hysteresis loop that the Fe nanodots have vortex structure and the dipolar interaction is dominant among them.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.600-600
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• 2013

We have fabricated Cr nanodot Schottky diodes utilizing AAO templates formed on n-Si substrates. Three different sizes of Cr nanodots (about 75.0, 57.6, and 35.8 nm) were obtained by controlling the height of the AAO template. Cr nanodot Schottky diodes showed a rectifying behavior with low SBHs of 0.17~0.20 eV and high ideality factors of 5.6~9.2 compared to those for the bulk diode. Also, Cr nanodot Schottky diodes with smaller diameters yield higher current densities than those with larger diameters. These electrical behaviors can be explained by both Schottky barrier height (SBH) lowering effects and enhanced tunneling current due to the nanoscale size of the Schottky contact. Also, we have fabricated Cr-Si nanorod Schottky diodes with three different lengths (130, 220, and 330 nm) by dry etching of n-Si substrate. Cr-Si nanorod Schottky diodes with longer nanorods yield higher reverse current than those with shorter nanorods due to the enhanced electric field, which is attributed to a high aspect ratio of Si nanorod.

• Journal of the Korean Vacuum Society
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• v.15 no.4
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• pp.427-433
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• 2006

We have fabricated nanodot arrays by using phase separated (PS- b- PMMA) diblock copolymer film and anodic aluminum oxide (AAO) membrane as templates with hexagonal arrays of cylindrical microdomains perpendicular to the substrate. Pulsed laser deposition technique was used to deposit various kinds of materials including Ag, Ni, ZnO, Si:Er, and Co/Pt onto Si substrates. The size and separation of nanodots correspond to those of the templates used, The density of nanodots was estimated to be $6{\times}10^{11}/cm^2$ and $1{\times}10^{10}/cm^2$ when the diblock copolymer and AAO were used, respectively. In particular, the optical properties of ZnO and Si: Er nanodot arrays were investigated and the strong photoluminescence at 380 nm and $1.54{\mu}m$ was observed from ZnO and Si:Er nanodot arrays, respectively.

• Journal of Powder Materials
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• v.23 no.4
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• pp.270-275
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• 2016

We report on an all-solution-processed hydrothermal method to control the morphology of ZnO nanostructures on Si substrates from three-dimensional hemispherical structures to two-dimensional thin film layers, by controlling the seed layer and the molar contents of surfactants during their primary growth. The size and the density of the seed layer, which is composed of ZnO nanodots, change with variation in the solute concentration. The ZnO nanodots act as heterogeneous nucleation sites for the main ZnO nanostructures. When the seed layer concentration is increased, the ZnO nanostructures change from a hemispherical shape to a thin film structure, formed by densely packed ZnO hemispheres. In addition, the morphology of the ZnO layer is systematically controlled by using trisodium citrate, which acts as a surfactant to enhance the lateral growth of ZnO crystals rather than a preferential one-dimensional growth along the c-direction. X-ray diffraction and energy dispersive X-ray spectroscopy results reveal that the ZnO structure is wurtzite and did not incorporate any impurities from the surfactants used in this study.

• Applied Microscopy
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• v.36 no.spc1
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• pp.25-33
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• 2006

Nanofabrication with finely focused ion and electron beams is reviewed, and position and size controlled fabrication of nano-metals and -semiconductors is demonstrated. A focused ion beam (FIB) interface attached to a column of 200keV transmission electron microscope (TEM) was developed. Parallel lines and dots arrays were patterned on GaAs, Si and $SiO_2$ substrates with a 25keV $Ga^+-FIB$ of 200nm beam diameter at room temperature. FIB nanofabrication to semiconductor specimens caused amorphization and Ga injection. For the electron beam induced chemical vapor deposition (EBI-CVD), we have discovered that nano-metal dots are formed depending upon the beam diameter and the exposure time when decomposable gases such as $W(CO)_6$ were introduced at the beam irradiated areas. The diameter of the dots was reduced to less than 2.0nm with the UHV-FE-TEM, while those were limited to about 15nm in diameter with the FE-SEM. Self-standing 3D nanostructures were also successfully fabricated.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.132-132
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• 2012

Depositing $CaF_2$[0.6% lattice-mismatch] on the Si(001)-$4^{\circ}$ off surface [composed of a single (001) domain with regularly-arrayed double-layer DB steps and located between (1 1 19) and (1 1 21)] held at $700^{\circ}C$, $CaF_2$ molecules are preferentially adsorbed on the dimers and dissociated to Ca and F atoms. Dissociated Ca atoms form a silicide layer of a $2{\times}3$ structure on the (001) terrace, while F atoms are desorbed from the surface. Once the terrace is covered with a calcium silicide layer, CaF starts to be adsorbed selectively on the steps, as shown in Fig. (a). With $CaF_2$ deposition exceeding 1 ML, the (1 1 17) surface having 1-D $CaF_2$ nanodots are formed as shown in Fig. (b). By the present STM study, it has been clearly disclosed that the calcium silicide interfacial layer is preformed prior to adsorption of $CaF_2$ on vicinal Si(001) surface.