• Proceedings of the Korean Magnestics Society Conference
• /
• 2003.06a
• /
• pp.24-24
• /
• 2003

Metallic magnetoelectronic devices have studied intensively and extensively for last decade because of the scientific interest as well as great technological importance. Recently, the scientific activity in spintronics field is extending to the hybrid devices using ferromagnetic/semiconductor heterostructures and to new ferromagnetic semiconductor materials for future devices. In case of the hybrid device, conductivity mismatch problem for metal/semiconductor interface will be able to circumvent when the device operates in ballistic regime. In this respect, spin-valve transistor, first reported by Monsma, is based on spin dependent transport of hot electrons rather than electron near the Fermi energy. Although the spin-valve transistor showed large magnetocurrent ratio more than 300%, but low transfer ratio of the order of 10$\^$-5/ prevents the potential applications. In order to enhance the collector current, we have prepared magnetic tunneling transistor (MTT) with single ferromagnetic base on Si(100) collector by magnetron sputtering process. We have changed the resistance of tunneling emitter and the thickness of baser layer in the MTT structure to increase collector current. The high transfer ratio of 10$\^$-4/ range at bias voltage of more than 1.8 V, collector current of near l ${\mu}$A, and magnetocurrent ratio or 55% in Si-based MTT are obtained at 77K. These results suggest a promising candidate for future spintronic applications.

• Bulletin of the Korean Chemical Society
• /
• v.35 no.5
• /
• pp.1491-1494
• /
• 2014

High-crystallinity poly(3-hexylthiophene) (P3HT) thin films were prepared by aging the precursor solutions, prepared using a good solvent, chloroform, at low temperatures prior to spin-casting. Lower solution temperatures significantly improved the molecular ordering in the spin-cast P3HT films and, therefore, the electrical properties of field-effect transistors prepared using these films. Solution cooling enhanced the electrical properties by shifting the P3HT configuration equilibrium away from random coils and toward more ordered aggregates. At room temperature, the P3HT molecules were completely solvated in chloroform and adopted a random coil conformation. Upon cooling, however, the chloroform poorly solvated the P3HT molecules, favoring the formation of ordered P3HT aggregates, which then yielded more highly crystalline molecular ordering in the P3HT thin films produced from the solution.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.1
• /
• pp.123-126
• /
• 2010

$Cu_2O$ nanoparticles-based films are fabricated by spin-coating on glass substrates and their optoelectronic characteristics are investigated in this study. The $Cu_2O$ films are nearly all-transparent as high as 98% in a wavelength range from 400 nm to 900 nm and three exciton peaks associated with the sublevels in the conduction band are observed at the wavelengths shorter than 400 nm in the absorption spectrum. Under the illumination of the 325 nm wavelength light, the photocurrent efficiency of the $Cu_2O$ film is $1.8\times10^5 {\mu}A/W$ at a voltage of 2.5 V in air.

• Journal of the Korean Magnetic Resonance Society
• /
• v.12 no.2
• /
• pp.103-110
• /
• 2008

Spin Hamiltonian for the paramagnetic center with a three-fold symmetry and high spin ($S{\geq}2$) multiplicity should contain the fourth order zero-field splitting (ZFS) terms. Electron magnetic resonance transition lines of the center with S = 5/2 are expected to split in a pair when the magnetic field is applied off the principal axes of ZFS, while they are superimposed when the magnetic field is applied parallel to the principal axes of ZFS. In this study we report that the transition lines of $Mn^{2+}$ centers at the three-fold symmetric sites in $LiNbO_3$, chemically equivalent but physically different, split in two due to the nonzero fourth order ZFS term.

• Journal of the Korean Regional Science Association
• /
• v.15 no.3
• /
• pp.53-68
• /
• 1999

This study aims to analyze the role of TST for regional development in terms of university-research institutes-industry interaction. In particular, it focuses on the spin-off activities from research institutes and universities and their support mechanisms. This study consists of following three sections. This study consists of following three sections. Firstly, we describe the role and characteristics of research institutes and universities as the foundation of high technology business spin-off activities in the region. Secondly, the mechanisms for active technology transfer and business incubation are identified in terms of university-research institute and industry interaction in TST. Thirdly, important lessons for the development of technopolis are suggested from the view point of experiences of TST.

• Journal of the Korean institute of surface engineering
• /
• v.34 no.3
• /
• pp.258-263
• /
• 2001

Siloxane thin films were fabricated on a silicon wafer by spin-coating using a siloxane solution made by the sol-gel process. Fluorine was doped using$ CF_4$ plasma treatment. The film was then annealed in-situ state in the nitrogen atmosphere. In order to examine the influence of annealing and fluorine doping on the siloxane thin film, thermogravimetric-differential thermal analysis (TG-DTA), Fourier transform-infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) were used and the dielectric constant was determined by the high-frequency capacitance-voltage method. Stable siloxane films could be obtained by in-situ annealing in a nitrogen atmosphere after $CF_4$ plasma treatment, and the dielectric value of the film was $\varepsilon$ 2.5.

• Journal of Magnetics
• /
• v.5 no.2
• /
• pp.50-54
• /
• 2000

NiMn-pinned spin valve films consisting of a layered glass/NiFe/Co/Cu/Co/NiFe/NiMn/Ta stack were made by do magnetron sputtering. After deposition, the structure was annealed in a series of cycles each including three hours at $220^\circ C, 2\times10^{-6}$ Torr, in a field of 350 Oe, to create an ordered antiferromagnetic structure in the NiMn layer and produce a strong unidirectional pinning field in the pinned magnetic layer, Optimum spin valve properties were obtained after seven annealing cycles, or 21 hours at $220^\circ C$, and were : MR ratio 1%, exchange coupling field 620 Oe, and coercivity of pinned layer 250 Oe. The exchange coupling field remained constant up to an operating temperature of $175^\circ C$, and the blocking temperature was about $380^\circ C$.

• Journal of Magnetics
• /
• v.13 no.1
• /
• pp.30-33
• /
• 2008

A highly sensitive, giant magnetoresistance-spin valve (GMR-SV) biosensing device with high linearity and very low hysteresis was fabricated by photolithography. The detection of magnetic nanoparticles and Fe-hemoglobin inside red blood cells using the GMR-SV biosensing device was investigated. When a sensing current of 1 mA was applied to the current electrode in the patterned active devices with an area of $2{\times}6{\mu}m^2$, the output signals were about 13.35 mV. The signal from even one drop of human blood and nanoparticles in distilled water was sufficient for their detection and analysis.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.3
• /
• pp.418-422
• /
• 2005

By introducing spin-coating method to the evaporation induced self-assembly (EISA) process, a simple and reproducible route in controlling the mesophase of silica thin films has been developed for the first time in this work. When a comparatively solvent-rich Si-sol (The atomic ratio of TEOS : F127 : HCl : $H_2O$ : EtOH = 1 : 0.006 : 0.2 : 9.2 : 30) was used as coating solution, the mesophase of resultant silica films was selectively controlled by adjusting the spin-on speed. The cubic mesophase has been obtained from the coating at a low rpm, such as 600 rpm, while the 2-D hexagonal mesophase is formed at a high rpm, such as 2,500 rpm. At a medium coating speed, a mixture of cubic and hexagonal mesophase has been found in the fabricated films. The present results confirm that the evaporation rate of volatile components at initial step is critical for the determination of mesopore structures during the EISA process.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.1885-1890
• /
• 2004

In this paper the numerical method with a zonal embedded grid system was applied to the spin-up flow within a semi-circular container. Flow visualization was also performed on a rotating table. The results show that at a low level of damping (i.e. low viscosity and high liquid depth) a cyclonic cell produced initially near the left-hand-side corner of the container moves along a wall and merged with the cell on the right-hand-side.