• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.48-48
• /
• 2007

P-type transparent conducting $CuGaO_2$ thin films have been prepared by DC/RF sputtering using Quartz(0001) and sapphire(0001) substrates. The target was fabricated by heating a stoichiometric mixture of CuO and $Ga_2O_3$ at 1373K for 12h under $N_2$ atmosphere. The film were deposited under mixture gas of Ar and $O_2(Ar:O_2=4:1)$ during 10~30min. and the as-deposited films were annealed at 1123K and $N_2$ atmosphere. Room temperature conductivity and the activation energy of the sintered body in the temperature range of 223K ~ 423K were 0 004S/cm, 1.9eV, respectively. XRD revealed that all of the as-deposited films were amorphous. Heating of the films deposited on Quartz substrates above 1123K resulted in crystallization with a second phase of $CuSiO_3$, which was assumed owing to reaction with Quartz substrate. The single phase of $CuGaO_2$ was obtained at the film deposited on the sapphire substrates. The transmittance after annealing of DC- and RF-sputtered films were 55~75% at 550nm. From the transmittance and reflectance measurement. the direct band gap of the DC/RF-sputtered films were 3.63eV and 3.57eV. and there was little difference between DC and RF sputtered films.

• Applied Chemistry for Engineering
• /
• v.35 no.1
• /
• pp.37-41
• /
• 2024

The coconut shell, a by-product of popular tropical fruit, is a promising material due to its interesting properties. The preparation of the composite consisted of conducting polymer and coconut shell using a simple wet method, and subsequent carbonization produced a carbonized material under a controlled carbonization cycle. In addition, its electrochemical performance as an anode in lithium-ion batteries was also investigated. The appearance of the obtained materials was observed with a scanning electron microscope. The internal structure of the carbon derived from the coconut shell under a controlled heating profile was analyzed using a Raman spectroscope. A simple electrical measurement based on the ohmic relationship showed that the carbonized product has a significant electrical conductivity. The application of the carbonized product as anode in a lithium-ion battery was tested using half-cell charge/discharge experiments. This article provides important information for future research regarding the recycling of fruit shells and food waste.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.06a
• /
• pp.93-94
• /
• 2009

The influences of $O_2$ partial pressure on electrical properties of transparent semiconducting indium zinc tin oxide thin films deposited at room temperature by magnetron sputtering have been investigated. The experimental results show that by varying the $O_2$ partial pressure during deposition, electron mobilities of IZTO thin film can be controlled between 7 and $25\;cm^2/Vs$. For conducting films, the carrier concentration and resistivity are ${\sim}\;10^{21}\;cm^{-3}$ and ${\sim}\;10^{-4}\;{\Omega}\;cm$, respectively. Concerning semiconducting films, under 12% $O_2$ partial fraction, the electron concentration is $10^{18}\;cm^{-3}$, showing the promising candidate for the application of transparent thin film transistors.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.21 no.2
• /
• pp.252-258
• /
• 2012

A study of terahertz waves was made for the nondestructive evaluation of FRP (Fiber reinforced plastics) composite materials. The terahertz systems were consisted of time domain spectroscopy (TDS) and continuous wave (CW). The composite materials investigated include both non-conducting polymeric composites and conducting carbon fiber composites. Terahertz signals in the TDS mode resembles that of ultrasound; however, unlike ultrasound, a terahertz pulse was not able to detect a material with conductivity. The CFRP (Carbon fiber reinforced plastics) laminates were utilized for confirming the experimentation in the terahertz NDE. In carbon composites the penetration of terahertz waves is quite limited and the detection of flaws is strongly affected by the angle between the electric field direction of the terahertz waves and the intervening fiber directions. A refractive index (n) was defined as one of mechanical properties; so a method was obtained in order solve the "n" in the material with non-conductivity. The usefulness and limitations of terahertz radiation are investigated for the NDE of FRP composites.

• Textile Coloration and Finishing
• /
• v.20 no.6
• /
• pp.82-86
• /
• 2008

Cooling function is definitely one of the most desirable attribute of clothing. In spite of the recent progress on phase changing material(PCM) research, the final products with sufficient amount of cooling capability have not yet to be developed in market. A new concept of cooling fabrics has been proposed by applying "Peltier effect" to textile materials. It occurs whenever electrical current flows through two dissimilar conductors; depending on the direction of current flow, the junction of the two conductors is absorbed or released heat. This effect has been tested on P-type and N-type conducting polymers. A P-type conductive polypyrrole coated fabric was synthesized by in-situ polymerization on plain weave PET to make conductive fabrics. And an N-type electrically conductive material was synthesized by treatment of MWNT and polyethyleneimine(PEI). A noticeable amount of temperature difference has been found on the fabrics.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.11a
• /
• pp.128-128
• /
• 2003

Electrochromism (EC) is defined as a phenomenon in which a change in color takes place in the presence of an applied voltage. Because of their low power consumption, high coloration efficiency, EC devices have a variety of potential applications in smart windows, mirror, and optical switching devices. An EC devices generally consist of a transparent conducting layer, electrochromic cathodic and anodic coloring materials and an ion conducting electrolyte. EC has been widely studied in transition metal oxides(e.g., WO$_3$, NiO, V$_2$O$\sub$5/) Among these materials, WO$_3$ is a most interesting material for cathodic coloration materials due to its lush coloration efficiency (CE), large dynamic range, cyclic reversibility, and low cost material. WO$_3$ films have been prepared by a variety of methods including vacuum evaporation, chemical vapor deposition, electrodeposition process, sol-gel synthesis, sputtering, and laser ablation. Sol-gel process is widely used for oxide film at low temperature in atmosphere and requires lower capital investment to deposit large area coating compared to vacuum deposition process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.22 no.7
• /
• pp.567-571
• /
• 2009

Polycrystalline ZnO and Ga doped ZnO (GZO) films are deposited on glass substrate by RF magnetron sputtering at room temperature. The characteristics of ZnO and GZO films are investigated with X-ray diffraction measurement, UV-VIS-NIR spectrophotometer $(250{\sim}1200nm)$ and hall measurement. The post-growth thermal treatment of these films is carried out in N2 ambient at $500^{\circ}C$ for 30 min and an hour. ZnO and GZO films have different changing behavior of structural and optical properties by annealing. To use transparent conductive films for solar cell, films should have not only high transmittance but also good electrical property. Although as deposited GZO films have electrical properties than ZnO films, GZO films have not good transmittance properties. Consequently, we succeed that the high transmittance of GZO films is improved by annealing process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.24 no.5
• /
• pp.355-358
• /
• 2011

As a II-IV compound semiconductor, ZnO has a wide band gap of 3.37 eV with transparent properties. Due to this transparent properties, ZnO materials can be also employed as the transparent conducting electrode materials. Recently, rapid progress has been made in the field of DSSC (dye sensitized solar cell)area. Therefore, strong demands have been required for the transparent electrodes with low temperature processing and cheap cost. In this paper, we will prepare ZnO thick films on the PET substrates for the electrode applications. We will investigate the structural and microstructure properties through the XRD, and SEM analysis, respectively. Also, we will study the electrical of specimens to apply the conducting electrode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.04c
• /
• pp.41-41
• /
• 2008

Al-doped ZnO (AZO) thin films have been fabricated by vertical in-line dc magnetron sputtering for transparent conducting oxides (TCOs) applications. The effects of substrate temperature and dc power on the characteristics of AZO thin films are investigated and also optimized the process conditions to get the best electrical and optical properties. The fabricated thin films show a good electrical and optical uniformity within ${\pm}5%$ over the whole area of substrate ($200mm\;{\times}\;200mm$) ; the minimum resistivity of $8\;{\times}\;10^{-4}\;{\Omega}cm$ and the average transmittance of 90% within the visible wavelength range. We have found that the band gap ($E_g$) increases with increasing substrate temperature and dc power, whereas the crystallinity is getting improved with increasing substrate temperature. The binding energy of Zn $2p_{3/2}$ and O 1s is observed to decrease as the substrate temperature increases.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.1096-1099
• /
• 2001

The basic design structure of RC-GCTs (Reserve-Conducting Gate-Commutated Thyristors) is firstly given in this paper. The bulk of wafer is punch-through (PT) type with high resistivity and narrow N-base width. The photo-mask was designed upon the turn-off characteristics of GCT and solution of separation between GCT and diode part. The center part of Si wafer is free-wheeling diode (FWD) and outer is GCT part which has 240 fingers totally. The switching performance of GCT was investigated by Dessis of ISE. The basic manufacture process of 2500V-4500V RC-GCTs was given in this work. Additionally, the local carrier lifetime control by 5Mev proton irradiation was adopted so as to not only to have the softness of reverse recovering for FWD but for reduction of turn-off losses of GCT as well.