• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.06a
• /
• pp.25-26
• /
• 2009

Pulsed-PECVD를 이용하여 상온에서 실리콘 나이트라이드(SiN) 박막을 증착하였다. 본 연구에서는, 60-100%의 duty ratio 변화에 따른 굴절률을 살펴보고, 굴절률에 대한 이온에너지의 영향을 분석했다. RF 소스파워는 900W로 고정하였고 $SiH_4-N_2$를 이용하였다. 이온에너지에 대한 정보는 non-invasive 이온 분석기를 이용하여 수집하였다. 측정된 이온에너지 변수는 high ion energy, low ion energy, high ion energy flux, low ion energy flux이며, 이를 이용해 또 다른 변수인 ion energy flux ratio를 계산하였다. Duty ratio의 감소에 따라 굴절률은 일반적으로 감소하였다. 또한 duty ratio의 감소에 따라 high ion energy는 증가하였다. 한편, 60-80%에서 굴절률은 이온에너지 flux의 비에 강한 의존성을 보였으며, 60%를 제외한 모든 duty ratio 구간에서 굴절률은 Nl에 강하게 영향을 알고 있는 것으로 유추되었다. 굴절률은 1.508와 1.714 사이에서 변화하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.06a
• /
• pp.292-292
• /
• 2009

OLED(Organic Light Emitting Device)는 LCD(Liquid Crystal Display)의 뒤를 잇는 차세대 디스플레이의 선두주자로서 자체발광형이기 때문에 백라이트 등의 보조광원이 불필요하며, 구동전압이 낮고 넓은 시야각과 빠른 응답속도 등의 특징을 가지고 있다. 또한 플렉서블 기판을 사용할 수 있어 차세대 디스플레이인 플렉서블 디스플레이에 적합하다. 플렉서블한 디스플레이를 만들기 위해서 플라스틱 기판에 OLED 물질을 사용하여 기존에 무겁고, 깨지기 쉬우며, 변형이 불가능한 유리로 만든 소자 보다 더 가볍고 깨지지 않고 변형이 가능한 플렉서블 디스플레이를 제작 할 수 있다. 그러나 플라스틱 기판은 매우 큰 투습율을 가지고 있어 OLED소자에 적용시키면 공기 중의 수분이나 산소와 접촉이 많아져 쉽게 산화되어 소자의 효율 및 수명이 짧아진다. 또한 OLED에 사용되는 유기물도 산소나 수분에 의해 특성이 급격히 저하되기 때문에 산소 및 수분의 차단은 필수적이다. 이러한 단점을 최소화하기 위해서 PECVD(Plasma Enhanced Chemical Vapor Deposition)로 만든 SiON(Silicon Oxynitride) 박막을 차단막(Passivation layer)으로 사용하였다. PECVD를 이용하여 SiON 박막을 증착시킬 때 RF Power, 공정압력, Distance의 변화에 따른 박막의 결정화도, 수분투습도, 광투과도 등의 특성을 FT-IR(Fourier Transform Infrared Spectroscopy), Ellipsometer, UV-visible Spectrophotometer, MOCON를 이용하여 SiON 박막의 특성을 고찰하였다.

• Electrical & Electronic Materials
• /
• v.16 no.9
• /
• pp.65.1-65
• /
• 2003

The interface of zirconium oxide thin films on silicon is analyzed in detail for their potential applications in the microelectronics. The formation of an interfacial layer of ZrSi$\sub$x/O$\sub$y. with graded Zr concentration is observed by the x-ray photoelectron spectroscopy and secondary ion mass spectrometry analysis. The as-deposited ZrO$_2$/ZrSi$\sub$x/O$\sub$y//Si sample is thermally stable up to 880$^{\circ}C$, but is less stable compared to the ZrO$_2$/SiO$_2$/Si samples. Post-deposition annealing in oxygen or ammonia improved the thermal stability of as-deposited ZrO$_2$/ZrSi$\sub$x/O$\sub$y/Si to 925$^{\circ}C$, likely due to the oxidation/nitridation of the interface. The as-deposited film had an equivalent oxide thickness of∼13 nm with a dielectric constant of ∼21 and a leakage current of 3.2${\times}$10e-3 A/$\textrm{cm}^2$ at 1.5V. Upon oxygen or ammonia annealing, the formation of SiO$\sub$x/ and SiH$\sub$x/N$\sub$y/O$\sub$z/ at the interface reduced the overall dielectric constants.

• Journal of the Korea Computer Industry Society
• /
• v.8 no.1
• /
• pp.17-22
• /
• 2007

Carbon nanotubes (CNTs) were grown by a thermal chemical vapor deposition (CVD) method, which has been regarded as one of the most promising candidates for the synthesis of CNTs due to low cost and high growth yield. The Ethylene $(C_2H_4)$, hydrogen $(H_2)$ and Argon(Ar) gases were used for the growth of CNTs at $700^{\circ}C$. As a catalyst for CNTs growth, Fe thin film and Iron nitrate and Molybdenyl acetylacetonate solution with alumina nano-particle were prepared on $SiO_2/Si$ substrate. The growth properties of CNTs were analyzed by SEM and AFM.

• Design & Manufacturing
• /
• v.6 no.1
• /
• pp.24-28
• /
• 2012

Friction and wear affect all processes involved in the extraction of materials and their conversion into finished products in the die applications such as drawing, extrusion etc. Originating phenomenon from the contact surface between the tool and workpiece, they are usually a hindrance to materials process operations which usually result in damaging the tools, increasing energy consumption, the contamination of processed material by wear particles and also some problems associated with technologies to control friction and wear. The most well established method to control friction and wear is by the application of lubricant such as fluorocarbon. Besides, a surface technique so-called surface modification can be applied to solve the tribology problems of the die applications for both the economical and ecological reasons. In this article, we applied DLC(diamond-like carbon) thin film on alumina ceramic for HT test using the PIID(plasma ion immersion deposition), 4 groups of test specimens were tested up to $200^{\circ}C$ which is a little higher than the normal working temperature of die application. Pin-on-disc tribo-tester was used to test the friction and surfaces were characterized by SEM and EDS and else, the morphology changes of DLC coatings were studied. The present work indicated that the DLC had a great potential to reduce the friction and wear in the alumina die application without lubricants.

• Mass Spectrometry Letters
• /
• v.7 no.1
• /
• pp.21-25
• /
• 2016

Dual-channel nano-electrospray has recently become an ionization technique of great promise especially in biological mass spectrometry. This unique approach takes advantage of the mixing processes that occurs during electrospray. Understanding in more detail the fundamental principles influencing spray formation further study of the origins of the mixing processes: (1) in a Taylor cone region, (2) in charged droplets or (3) in both environments. The dual-channel emitters were made from borosilicate theta-shape glass tubes (O.D. 1.2 mm) and had a tip diameters of less than 4 μm. Electrical contact was achived by deposition of a thin film of an appropriate metal onto the surface of the emitter. The experimental investigation of the Taylor cone formation in a dual-channel electrospray emitter has been carried out by injection of polystyrene beads (diameter 3 μm) at very low concentrations into one of the channels of the non-tapered theta-glass tubes. High-speed camera experiments were set up to visualize the mixing processes in Taylor cone regions for dual-channel emitters. Mass spectra from dual nano-electrospray are presented.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.1491-1492
• /
• 2011

In this study, we investigated about the effect of hole transport layer materials(${\alpha}$-NPD, TPD) depending on the electrical properties of organic light emitting diode. In deposition method, we used thermal evaporation and it was a method for performing thin film by attaching vaporizing a molecule to substrate in a high thermal and vaccum. We analyzed luminance, current density, external quantum efficiency and current efficiency in 40 [nm] as optimization thickness of ${\alpha}$-NPD and TPD. In result of experiment, maximum luminance of TPD had 1.1 times higher than ${\alpha}$-NPD, but ${\alpha}$-NPD had luminance, external quantum efficiency, and current efficiency higher than TPD in low operating voltage. Actually, ${\alpha}$-NPD had efficiency higher than TPD in low operating voltage.

• Transactions on Electrical and Electronic Materials
• /
• v.15 no.6
• /
• pp.315-319
• /
• 2014

In this paper, we investigate visible light stress instability in radio frequency (RF) sputtered a-IGZO thin film transistors (TFTs). The oxygen flow rate differs during deposition to control the concentration of oxygen vacancies, which is confirmed via RT PL. A negative shift is observed in the threshold voltage ($V_{TH}$) under illumination with/without the gate bias, and the amount of shift in $V_{TH}$ is proportional to the concentration of oxygen vacancies. This can be explained to be consistent with the ionization oxygen vacancy model where the instability in $V_{TH}$ under illumination is caused by the increase in the channel conductivity by electrons that are photo-generated from oxygen vacancies, and it is maintained after the illumination is removed due to the negative-U center properties.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2000.11a
• /
• pp.36-39
• /
• 2000

A small electrical potential difference which appears on any solid body when subjected to illumination by a modulated light beam generated by laser is called photocharge voltage(PCV)[1,2]. This voltage is proportional to the induced change in the surface electrical charge and is capacitatively measured on various materials such as conductors, semiconductors, ceramics, dielectrics and biological objects. The amplitude of the detected signal depends on the type of material under investigation, and on the surface properties of the sample. In photocharge voltage spectroscopy measurements[3], the sample is illuminated by both a steady state monochromatic bias light and the pulsed laser. The monochromatic light is used to created a variation in the steady state population of trap levels in the surface and space charge region of semiconductor samples which does result in a change in the measured voltage. Using this technique the spatial variation of PCV can be utilized to evalulate the surface conditions of the sample and the variation of the PCV due to the monochromatic bias light are utilized to charactrize the surface states. A qualitative analysis of the proposed measuremen is present along with experimental results performed on amorphous silicon samples. The deposition temperature was varied in order to obtain samples with different structural, optical and electronic properties and measurements are related to the defect density in amorphous thin film.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.18 no.6
• /
• pp.593-600
• /
• 2013

The asymmetric pulsed DC reactive magnetron sputtering system is widely used for the high quality plasma sputtering process such as a thin film deposition. In asymmetric pulsed DC power supply a reverse voltage is applied to the target periodically to minimize arc discharging effect. When sputtering in the mid-frequency range (20-350 kHz), the periodic target voltage reversals suppress arc formation at the target and provide long-term process stability. Thus, high quality, defect-free coatings of these materials can now be deposited at competitive rates. In this paper, a new style asymmetric pulsed DC power supply including mid-transformer is presented. In the proposed, an energy recovery circuit is adopted to reduce the mutual inductance of the transformer. As a result, the system dynamics of the voltage control loop is increased highly and the non-linear voltage boosting effect of the conventional system is removed. This work was proved through simulation and laboratory based experimental study.