• Journal of Sensor Science and Technology
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• v.16 no.5
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• pp.377-383
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• 2007

We describe the fabrication and characterization of a doubly clamped multi-walled carbon nanotube (MWNT). The device was assembled by an application of electric field in solution. The MWNT was clamped on end of metal trench electrodes in solution and deposited with additional platinum (Pt) on edge of electrode for firmly suspending the MWNT by focused ion beam (FIB). The MWNTs range of diameter and length were 100 to 150 nm and 1.5 to $2{\mu}m$, respectively. Electrical characteristics of fabricated devices were measured by I-V curve and impedance analysis. The mechanical deformation was observed by resistivity in high air pressure. Resonant frequency around 6.8 MHz was detected and resistivity was linearly varied according to the magnitude of air pressure. This device could have potential applications in nanoelectronics and various sensors.

• The Journal of Engineering Geology
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• v.28 no.1
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• pp.69-79
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• 2018

The Korean government attempts to reduce $CO_2$ emissions by 37% to 314.7 Mt $CO_2$, down from the estimated 850.6 Mt $CO_2$ until 2030 in order to confront green house effect. In this context, in 2014, Korean government launched $CO_2$ Storage Environmental Management Research (K-COSEM) Center for carrying out pilot-scale research on $CO_2$ leakage from underground $CO_2$ storage facilities. For the detection of $CO_2$ leakage, it is necessary to identify hydrologeological and geophysical characteristics of the subject area. In the study site of Naesan-ri, Daeso-myeon, Eumseong-gun, Chungbuk Province, two times injection tests (June 28-July 24, 2017 and August 07-September 11, 2017) of $CO_2$ and $SF_6$ dissolved waters, respectively, was conducted to understand the leakage behavior of $CO_2$ from underground. The injection well was drilled to a depth of 24 m with a 21-m casing and screen interval of 21~24 m depth. Two times resistivity surveys on August 18, 2017 and September 1, 2017, were conducted for revealing the flow of the injected water as well as the electrical properties of the study site. The study results have shown that the high-resistivity zone and the low-resistivity zone are clearly contrasted with each other and the flow direction of the injected water is similar to natural groundwater flow. Besides, the low resistivity zone is widely formed from the depth of injection to the shallow topsoil, indicating that the weathered zone of high permeability has high $CO_2$ leakage potential.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.10
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• pp.1-8
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• 2003

Copper thin films were deposited on a Cu/Ta/Si substrate using the electroplating technique. Deposition rate was about 200 nm/min in proportion to current density and in inverse proportion to flow rate. Resistivity of copper thin film was approximately 2.1 ${\mu}$Ωcm and Int$\sub$(111)//Int$\sub$(200)/ ratio of copper film was 5.4 and no significant impurities were detected. After the deposition, electroplating copper films were annealed at various temperatures in a background pressure of 10$\^$-3/ torr. The resistivity of copper thin films were improved by ∼17 % and texture was improved by ∼40 % after annealing at 170$^{\circ}C$. The stress in films was not reduced much after annealing below 170$^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.525-528
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• 2001

ZnO:Al thin film can be used as a transparent conducting oxide(TCO) which has low electric resistivity and high optical transmittance for the front electrode of amorphous silicon solar cells and display devices. This study of electrical, crystallographic and optical properties of Al doped ZnO thin films prepared by Facing Targets Sputtering(FTS), where strong internal magnets were contained in target holders to confine the plasma between the targets, is described. Optimal transmittance and resistivity was obtained by controlling flow rate of $O_2$ gas and substrate temperature. When the $O_2$ gas rate of 0.3 and substrate temperature $200^{\circ}C$, ZnO:Al thin film had strongly oriented c-axis and lower resistivity( < $10^{-4}{\Omega}-cm$ ).

• Electrical & Electronic Materials
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• v.10 no.2
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• pp.126-133
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• 1997

In order to apply for the gas sensing layer and the piezoelectric thin film devices, we studied the effects of magnetron sputtering conditions and annealing temperature on the electrical and structual characteristics of the ZnO thin film. The optimal deposition conditions, in order to obtain a c axis of the ZnO (002) phase thin film which is perpendicular to SiO$_{2}$/Si substrate, were like these ; substrate temperature 150.deg. C, chamber pressure 2 mtorr, R.F. power 300 watts, gas flow ratio 0.4[O$_{2}$(Ar + $O_{2}$)]. When the ZnO thin film was annealed in 600.deg. C, $O_{2}$ gas ambient for 1 hr, the resistivity was 2.6 x 10$^{2}$.ohm.cm and the grain size of ZnO thin film was less than 1 .mu.m. So the ZnO thin film acquired from above conditions can apply for the gas sensing layer which require a c axis perpendicular to the substrate surface.

• Geophysics and Geophysical Exploration
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• v.7 no.1
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• pp.33-40
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• 2004

Numerical and laboratory studies have been conducted to test the ability of Electrical Resistance Tomography-a technique used to map the electrical resistivity of the subsurface-to delineate contaminant plumes. Two-dimensional numerical models were created to investigate survey design and resolution. Optimal survey design consisted of both downhole and surface electrode sites. Resolution models revealed that while the bulk fluid flow could be outlined, small-scale fingering effects could not be delineated. Laboratory experiments were conducted in a narrow glass tank to validate theoretical models. A visual comparison of fluid flow with ERT images also showed that, while the bulk fluid flow could be seen in most instances, fine-scale effects were indeterminate.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.67-68
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• 2006

We prepared the AZO thin film with different $O_2$ gas flow rate. the AZO thin films were deposited on glass substrate at room temperature, working gas pressure of 1mTorr. the electrical, structural and optical properties of AZO thin films were investigated by using Hall Effect measurement system, X-ray Diffractometer (XRD) and UV-VIS spectrometer. From the results, we could obtain that AZO thin film with low resistivity of $8.5{\times}10^{-4}{\Omega}cm$ was exhibited in specific $O_2$ gas flow rate. Also, the transmittance of over 80% in visible range was observed in specific $O_2$ gas flow rate. In all of the AZO thin film with the transmittance of over 80%, diffraction peak of (002) direction was observed, while amorphous peak was observed in the AZO thin film with the low transmittance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.463-466
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• 2001

This detailed study of electrical, crystallographic and optical properties in Al doped ZnO thin films prepared by Facing Targets Sputtering(FTS), where strong internal magnets were contained in target holders to confine the plasma between the targets is described. Optimal transmittance and resistivity was obtained by controlling flow ratio of O$_2$gas. When the O$_2$ gas ratio of 0.25 and substrate temperature R.T., ZnO:Al thin film deposited had strongly oriented c-axis and the lower resistivity ( <10$\^$-4/ $\Omega$cm). The optical transmittance was above 80% in visible range.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1393-1395
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• 2001

DLC films are deposited by using a modified FCVA system. Carbon amorphous network, surface roughness, internal compressive stress, resistivity, and Hall mobility are studied as a function of nitrogen flow rate (0 $\sim$ 10 sccm). As the nitrogen content is increased in the carbon network, the size of $sp^2$ clusters is increased, the internal compressive stress is decreased, and the resistivity is remarkably decreased. The RMS values of the surface roughness are measured to be in the range of 0.2$\sim$0.5nm. The Hall mobility of DLC film with 3 sccm of nitrogen added is 3.22 $cm^2/V{\cdot}$s.

• Journal of the Korean institute of surface engineering
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• v.29 no.6
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• pp.803-808
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• 1996

Material and electrical characteristies of copper thin films prepared by metal organic chemical vapor deposition (MOCVD) have been investigated for interconnection applications in ultra large scale integration circuits (ULSI). The copper films have been deposited a TiN substrates using a metal organic precursor, hexafluoro acetylacetonate trimethyvinylsilane copper, VTMS(hfac)Cu (I). Deposition rate, grain size, surface morphology, and electrical resistvity of the copper films have been measuredfrom samples prepared at various experimental conditions, which include substrate temperature, chamber pressure, and carrier gas flow rate. Results of the experiment showed that the electrical property of the copper films is closely related to the crystallinity of the films. Lowest electrical resistivity, $2.4{\mu}{\Omega}.cm$ was obtained at the substrate temperature of $180^{\circ}C$, but the resistivity slightly increased with increasing substrate temperature due to the carbon content along the copper grain boundaries.