• Korean Journal of Materials Research
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• v.8 no.12
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• pp.1182-1189
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• 1998

High quality $TiN/TiSi_2$-bilayers were formed on the Si(100) substrate at room temperature and at $600^{\circ}C$ first by coevaporation of stoichiometric Si and Ti(Si:Ti = 2:1) fellowed by Ti reactive deposition in N, gas ambient, and in situ annealing in ultrahigh vacuum. Stoichiometric $Ti_{0.}N_{0.5}$, films with (111) texture and $C54-TiSi_2$ films were grown by annealing at temperatures above $700^{\circ}C$. $TiN/C54-TiSi_2$/Si(100) interface was clear and flat without agglomoration, and $CS4-TiSi_2$ film was epitxailly grown. The sheet resistance of the $TiN/TiSi_2$- bilayer decreased as the annealing temperature increased and about $2.5\omega/\textrm{cm}^2$ was obtained from the sample annealed over $700^{\circ}C$.

• Progress in Superconductivity
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• v.9 no.1
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• pp.80-84
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• 2007

Charcoal was used as a carbon source for improving the critical current density of $MgB_2$ and the effect of annealing temperature on the $J_c$ of $MgB_2$ was investigated. The charcoal powder used in this study was $1{\sim}2$ microns in size and was prepared by wet attrition milling. $MgB_2$ bulk samples with a nominal composition of $Mg(B_{0.95}C_{0.05})_2$ were prepared by in situ process of Mg and B powders. The powder mixture was uniaxially compacted into pellets and heat treated at temperatures of $650^{\circ}C\;-\;1000^{\circ}C$ for 30 minutes in flowing Ar gas. It was found that superconducting transition temperature of $Mg(B_{0.95}C_{0.05})_2$ decreased by charcoal additions which indicates the carbon substitution for boron site. $J_c$ of $Mg(B_{0.95}C_{0.05})_2$ was lower than that of the undoped $MgB_2$ at the magnetic fields smaller than 4 Tesla, while it was higher than that of the undoped sample especially at the magnetic field higher than 4 T. High temperature annealing seems to be effective in increasing $J_c$ due to the enhanced carbon diffusion into boron sites.

• Tunnel and Underground Space
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• v.17 no.6
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• pp.493-502
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• 2007

Measurements of hydraulic conductivity are point or interval values, and are highly limited in their number. Meanwhile, results of geophysical prospecting can provide the information of spatial variation of geology, and abundant in number. In this study, it was aimed to develop a data integration tool for constructing a hydraulic conductivity map by integrating geophysical data and hydraulic conductivity measurements. The developed code employed a geostatistical optimization method, simulated annealing (SA), and consists of 4 distinct computation modules by which from exploratory data analysis to postprocessing of the simulation were processed. All these modules are equipped with Graphical User Interface (GUI). Validation of the developed code was evaluated in-situ in characterizing hydraulic characteristics of highly permeable fractured zone.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.63-66
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• 1999

We fabricated ramp-edge Josephson junctions with barriers formed by interface treatments instead of epitaxially grown barrier layers. Low-dielectric Sr$_2AITaO_6$(SAT) layer was used as an ion-milling mask as well as an insulating layer for the ramp-edge junctions. An ion-milled YBa$_2Cu_3O_{7-x}$ (YBCO)-edge surface was not exposed to solvent through all fabrication procedures. The barriers were produced by structural modification at the bottom YBCO edge using plasma treatment prior to deposition of the top YBCO electrode. We investigated the effects of pre-annealing and post-annealing on the characteristics of the interface-treated Josephson junctions. The junction parameters were improved by using in-situ RF plasma cleaning treatment.

• Korean Journal of Materials Research
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• v.14 no.11
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• pp.821-827
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• 2004

Titanium oxide thin films were prepared on Si(100) substrates by R.F. magnetron reactive sputtering at $30\sim200watt$ R.F power range, and annealed at $600^{\circ}C\sim800^{\circ}C$ for 1 hour. The properties of $TiO_2$ thin films were analyzed using x-ray, ${\alpha}-step$, ellipsometer, scanning electron microscopy, and FT-IR spectrometer. Upon in-situ depositions, the initial phase of $TiO_2$ thin film showed non-crystalline phase at R.F. power $30\sim100$ watt. The crosssection of $TiO_2$ thin films were sbserved to be the columnar structure. With the increasing R.F power and annealing temperature, the grain size, crystallinity, refractive index, and void size of titanium oxides showed a tended to increase. The FT-IR transmittance spectra of titanium oxide thin films have the obsorption band of Ti-O bond, Si-O bond, Si-O-Ti bond and O-H bond. With the increase of R.F. power and annealing temperature, these films have the stronger bond structures. It is considered that such a phenomena is due to phase transition and good crystallinity

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.397-398
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• 2005

Ferroelectric Lithium niobate ($LiNbO_3$) thin films are fabricated on $Al_2O_3$(0001) substrate using Pulsed Laser Deposition (PLD). The various deposition conditions such as substrate temperature, oxygen pressure, and post annealing condition are investigated to deposite c-axis oriented $LiNbO_3$ thin films. Highly c-axis oriented thin films are obtained under the conditions of working pressure of 100 mTorr, deposition for 10 min at $450^{\circ}C$, and in-situ annealing for 40 min. The $LiNbO_3$ thin films are chemically etched after electric poling and the etched configurations are studied by scanning electron microscope (SEM).

• Journal of the Korean Vacuum Society
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• v.9 no.2
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• pp.155-161
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• 2000

BN films composed of c-BN(70%) and h-BN(30%) phases have been synthesized by the ion beam assisted deposition (IBAD) process and stabilized by post-annealing. Boron was e-beam evaporated at 1.2 $\AA$/sec and nitrogen was ionized and accelerated at about 100 eV by the end-hall type ion gun. Substrates were negatively biased by DC 400 and 500 V, respectively, and heated at $700^{\circ}C$. Synthesized BN films were in-situ post-annealed at 700 or $800^{\circ}C$, respectively, for 1 hr without breaking vacuum. BN films without post-annealing were peeled off from substrates immediately when they were exposed to the air while those with post-annealing at $800^{\circ}C$ were stabilized. Post annealing reduced the film stress from 4.9 GPa to 3.4 GPa, but no considerable stress release in the c-BN phase was observed, contrary to previous reports that the stress relaxation in the c-BN phase is the main mechanism for the stabilization. Structural and chemical relaxation of non c-BN phase is supposed to be responsible for the film stress reduction and, in turn, stabilization, especially when the c-Bn content of the film is not high.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.1
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• pp.44-50
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• 1993

In an attempt to improve the electrical characteristics of tantalum pentoxide dielectric film, silicon substrate was reacted with a nitrogen plasma to form a silicon nitride of 50.angs. and then tantalum pentoxide thin films were formed by reactive sputtering in the same chamber. Breakdown field and leakage current density were measured to be 2.9 MV/cm and 9${\times}10^{8}\;A/cm^{2}$ respectively in these films whose thickness was about 180.angs.. With annealing at rectangular waveguides with a slant grid are investigated here. In particular, 900.deg. C in oxygen ambient for 100 minutes, breakdown field and leakage current density were improved to be 4.8 MV/cm and 1.61.6${\times}10^{8}\;A/cm^{2}$ respectively. It turned out that the electrical characteristics could also be improved by oxygen plasma post-treatment and the conduction mechanism at high electric field proved to be Schottky emission in these double-layered films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.59-62
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• 1998

Thermal treatment dependences of MFS devices in $BaMgF_4$ on Si structures have been investigated. $BaMgF_4$ thin films have been directly deposited on the p-Si(100) wafers at a low temperature of $300^{\circ}$ in an ultra high vacuum(UHV) system. After in-situ post-deposition annealing was conducted for 20 s at $650^{\circ}$, bias and temperature were applied to $BaMgF_4/Si$ structures. Although X-ray diffraction analysis showed that the films were polycrystalline in nature before and after bias temperature, the C-V properties were some different between with and without bias-temperature treatment.

• Journal of Magnetics
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• v.11 no.1
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• pp.1-4
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• 2006

We report on the growth, structural and transport properties of zinc-blende CrAs/GaAs/MnAs/GaAs multilayers on GaAs(001) substrates. Structural analyses using in-situ reflection high-energy electron diffraction and exsitu cross-sectional transmission electron microscopy confirmed the realization of a zinc-blende crystal structure. Room temperature Hall measurements reveal that the as-grown multilayer exhibits p-type conductivity with a very low resistivity of $0.052\;\omega{cm}$, a high carrier concentration of $6.2X10^{19}\;cm^{-3}$ and a Hall mobility of $1.8\;cm^2/Vs$. We also observed a clear decrease of the resistivity in samples after low temperature annealing.