• 정보저장시스템학회:학술대회논문집
• /
• 2005.10a
• /
• pp.185-189
• /
• 2005

We reported here nano-scale electrical phase-change recording in amorphous $Ge_2Sb_2Te_5$ media using an atomic force microscope (AFM) having conducting probes. In recording process, a pulse voltage is applied to the conductive probe that touches the media surface to change locally the electrical resistivity of a film. However, in contact operation, tip/media wear and contamination could major obstacles, which degraded SNR, reproducibility, and lifetime. In order to overcome tip/media wear and contamination in contact mode operation, we adopted the W incorporated diamond-like carbon (W-DLC) films as a protective layer. Optimized mutilayer media were prepared by a hybrid deposition system of PECVD and RF magnetron sputtering. When suitable electrical pulses were applied to media through the conducting probe, it was observed that data bits as small as 25 nm in diameter have been written and read with good reproducibility, which corresponds to a data density of $1 Tbit/inch^2$. We concluded that stable electrical phase-change recording was possible mainly due to W-DLC layer, which played a role not only capping layer but also resistive layer.

• Journal of the Korean Vacuum Society
• /
• v.9 no.3
• /
• pp.237-241
• /
• 2000

The structural, electrical and etching characteristics of Al alloy thin film with low impurity concentrations AlNd deposited by using do magnetron sputtering deposition are investigated for the applications as gate bus line in the TFt-LCD panel. And ITO thin film was deposited on AlNd, then the contact resistance was measured by Kelvin resistor. The deposited thin films show the decrease of resistivity and the increase of grain size after the RTA at $300^{\circ}C$ for 20 min. Moreover, the resistivity of AlNd does not show appreciable grain size dependence after RTA. It is concluded that the decrease of resistivity after RTA is due to the increase of grain size. The annealed AlNd is found to be hillock free. The etching profiles of AlNd was good and the minimun contact resistance was about $110\;{\mu\Omega}cm$. Calculation results reveal that the AlNd (2wt.%) thin film can be applicable to 25" SXGA class TFT-LCD panels.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.30 no.5
• /
• pp.411-422
• /
• 2010

Self-sensing on micro-failure, dispersion degree and relating properties, of carbon nanotube(CNT)/epoxy composites, were investigated using wettability, electro-micromechanical technique with acoustic emission(AE). Specimens were prepared from neat epoxy as well as composites with untreated and acid-treated CNT. Degree of dispersion was evaluated comparatively by measuring volumetric electrical resistivity and its standard deviation. Apparent modulus containing the stress transfer was higher for acid-treated CNT composite than for the untreated case. Applied cyclic loading responded well for a single carbon fiber/CNT-epoxy composite by the change in contact resistivity. The interfacial shear strength between a single carbon fiber and CNT-epoxy, determined in a fiber pullout test, was lower than that between a single carbon fiber and neat epoxy. Regarding on micro-damage sensing using electrical resistivity measurement with AE, the stepwise increment in electrical resistivity was observed for a single carbon fiber/CNT -epoxy composite. On the other hand, electrical resistivity increased infinitely right after the first carbon fiber breaks for a single carbon fiber/neat epoxy composite. The occurrence of AE events of added CNT composites was much higher than the neat epoxy case, due to micro failure at the interfaces by added CNTs.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.312-312
• /
• 2013

GaN based light emitting diodes (LEDs) are important devices that are being used extensively in our daily life. For example, these devices are used in traffic light lamps, outdoor full-color displays and backlight of liquid crystal display panels. To realize high-brightness GaN based LEDs for solid-state lighting applications, the development of p-type ohmic electrodes that have low contact resistivity, high optical transmittance and high refractive index is essential. To this effect, indiumtin oxide (ITO) have been investigated for LEDs. Among the transparent electrodes for LEDs, ITO has been one of the promising electrodes on p-GaN layers owing to its excellent properties in optical, electrical conductivity, substrate adhesion, hardness, and chemical inertness. Sputtering and e-beam evaporation techniques are the most commonly used deposition methods. Commonly, ITO films on p-GaN by sputtering have better transmittance and resistivity than ITO films on p-GaN by e-bam evaporation. However, ITO films on p-GaN by sputtering have higher specific contact resistance, it has been demonstrated that this is due to possible plasma damage on the p-GaN in the sputtering process. In this paper, we have investigated the advanced sputtering using plasma damage-free p-electrode. Prepared the ITO films on the GaN based LEDs by e-beam evaporation, normal sputtering and advanced sputtering. The ITO films on GaN based LEDs by sputtering showed better transmittance and sheets resistance than ITO films on the GaN based LEDs by e-beam evaporation. Finally, fabricated of GaN based LEDs by using advanced sputtering. And compared the electrical properties (measurement by using C-TLM) and structural properties (HR-TEM and FE-SEM) of ITO films on GaN based LEDs produced by e-beam evaporation, normal sputtering and advanced sputtering. As a result, It is expected to form plasma damage free-electrode, and better light output power and break down voltage than LEDs by e-beam evaporation and normal sputter.

• Composites Research
• /
• v.29 no.5
• /
• pp.262-268
• /
• 2016

In this work, the pitch-based carbon paper (P-CP) was prepared by re-impregnating of binder pitches and PAN-based milled carbon fibers (MCF) at low temperature carbonization process. The influence of MCF content on physicochemical properties of MCF/P-CP was investigated. As a result, the tensile strength of MCF/P-CP was increased sharply from 10 wt.% to 20 wt.% of MCF. Also, the increase of MCF content led to the decrease of interfacial contact resistivity and the improvement of electrical and thermal conductivity of MCF/P-CP. These results were probably due to the increase of density of MCF/P-CP, resulting in the formation of electrically and thermally conductive paths of the carbon paper.

• Proceedings of the KIEE Conference
• /
• 2001.11a
• /
• pp.112-114
• /
• 2001

In this letter, we report on the investigation of Si/Ti, Pt/Si/Ti, Co/Si/Ti Ohmic contacts to p-type 4H-SiC. The contacts were formed by a 2-step vacuum annealing at $550^{\circ}C$ for 5 min, $850^{\circ}C$ for 2 min respectively. The contact resistances were measured using the transmission line model method, which resulted in specific $10^{-4}{\Omega}cm^2$, and the physical properties of the contactcontact resistivities in the $9.2{\times}10^{-4}$, $7.1{\times}10^{-4}$ and $4.5{\times}s$ were examined using microscopy, AES(auger electron spectroscopy). AES analysis has shown that, at this anneal temperature, there was a intermixing of the Ti and Si, migration of into SiC. Overlayer of Pt, Co had the effect of decreasing the specific contact resistivity and improving the surface morphology of the annealed contact.

• Korean Journal of Materials Research
• /
• v.3 no.6
• /
• pp.661-667
• /
• 1993

Effects of $SiH_4//WF_6$(=R) ratio on the electrical properties of W films such as resistvity, contact resistance, junction leakage current in the selective W CVD technology for contact barrier metal were investigated with the emphasis on the role of $\alpha$-W Resistivity of W increases with increasing R, which is primarily due to the phase transformation from $\alpha$-W to , $\alpha$-W. $\alpha$-W found in the SiH4 reduced CVD W film is stabilized by Si incorporated into the W film rather than by oxygen. $\alpha$-W is found in the W film deposited on the Si substrate for high R, while $\alpha$-W is not found in the W film deposited on the TiN substrate even for high R. Also junction leakages increase with increasing R, which is caused not only by the vertical Si consumption but also the lateral Si consumption.

• Proceedings of the KIEE Conference
• /
• 1995.07c
• /
• pp.1174-1177
• /
• 1995

In this paper, electrical properties CdS/CdTe heterojunction solar cell prepared by electron beam evaporation method were investigated. Crystal structure of CdS films deposited at substrate temperature of $50{\sim}250^{\circ}C$ was hexagonal type with preferential orientation of the (002)plane parallel to the substrate. Optical transmittance of the CdS film is increasing and resistivity is decreasing with increasing subsrate temperature. CdS/CdTe Solar cell characteristics were improved by increasing of substrate and annealing temperature. However, low efficiency due to small Jsc, Voc below 0.3 $mA/cm^2$ and 430 mV are observed. Low efficiency is contributed to be high resistance of CdTe films and contact.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.853-854
• /
• 2006

Warm compaction powder metallurgy was used to produce a $Ti_3SiC_2$ particulate reinforced Cu matrix composite. Fabrication parameters and warm compaction behaviors of Cu powder were studied. Based on the optimized fabrication parameters a Cu-based electrical contact material was prepared. Results showed that in expend of some electrical conductivity, addition of $Ti_3SiC_2$ particulate increased the hardness, wear resistivity and anti-friction ability of the sintered Cu-base material.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1998.06a
• /
• pp.199-202
• /
• 1998

In examining application of polymer as electrical insulators, it is very important to perform accelerated aging test substituted the process which polymer insulator is degraded for long-time by the process of short-time. The purpose of this paper is to examine the properties of water degradation which affect on the efficiency of epoxy insulator. To do this, the surface properties on epoxy insulating material have been investigated after long-time accelerated degradation in boiling water condition. The experimental results showed the contact angle and surface resistivity after treatment to decrease the sample of water treatment. In dielectric properties, dielectric constant was increased by the aging development with water treatments.