• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.899-901
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• 2009

The magnesium fluoride ($MgF_2$) has very higher optical transmission than oxide or nitride material applied for gas barrier, so we manufactured Mg-Zn-F films with Mg-Zn-F target mixed in the various ratio of $MgF_2$ to Zn and characterized films' properties. Zn is used to increase packing density of barrier film. Thickness and optical transmission of Mg-Zn-F are 200 nm and over 90 %, respectively. The result of water vapor transmission rate at 38, RH 90 ~ 100% of the Mg-Zn-F film deposited with 4 : 6 ($MgF_2$ : Zn) ratio target reached below $1{\times}10^{-3}g$/($m^2{\cdot}day$), measuring limit of instrument.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.76.1-76.1
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• 2013

Atomic Layer Deposition (ALD) has remarkably developed in semiconductor and nano-structure applications since early 1990. Now, the advantages of ALD process are well-known as controlling atomic-level-thickness, manipulating atomic-level-composition control, and depositing impurity-free films uniformly. These unique properties may accelerate ALD related industries and applications in various functional thin film markets. On the other hand, one of big markets, Display industry, just starts to look at the potential to adopt ALD functional films in emerging display applications, such as transparent and flexible displays. Unlike conventional ALD process strategies (good quality films and stable precursors at high deposition processes), recently major display industries have suggested the following requirements: large area equipment, reasonable throughput, low temperature process, and cost-effective functional precursors. In this talk, it will be mentioned some demands of display industries for applying ALD processes and/or functional films, in terms of emerging display technologies. In fact, the AMOLED (active matrix organic light emitting diode) Television markets are just starting at early 2013. There are a few possibilities and needs to be developing for AMOLED, Flexible and transparent Display markets. Moreover, some basic results will be shown to specify ALD display applications, including transparent conduction oxide, oxide semiconductor, passivation and barrier films.

• 한국광학회지
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• 제1권1호
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• pp.73-86
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• 1990

The technique of Spectroscopic Ellipsometry (SE) has been examined with emphasis on its inherent sensitivity to the existence of thin films or surface equivalents. A brief review of related theories like the Fresnel reflection coefficients, the effect of a multilayer upon reflectivities, together with the validity of the effective medium theory and the modelling procedure, is followed by a short description of the experimental setup of a rotating polarizer type SE as well as the necessful expressions which lead to tan and cos. Out of its numerous, successful applications, a few are exampled to convince a reader that SE can be applied to a variety of research fields related to surface, interface and thin films. Specifically, those are adsorption and/or desorption on metals or semiconductors, oxidation process, formation of passivation layers on an electrode, thickness determination, interface between semiconductor and its oxide, semiconductor heterojunctions, surface microroughness, void distribution of dielectric, optical thin films, depth profile of multilayered samples, in-situ or in-vitro characterization of a solid surface immersed in electrolyte during electrochemical, chemical, or biological treatments, and so on. It is expected that the potential capability of SE will be widely utilized in a very near future, taking advantage of its sensitivity to thin films or surface equivalents, and its nondestructive, nonperturbing characteristics.

• 한국재료학회지
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• 제25권8호
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• pp.391-397
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• 2015

NiO catalysts/$Al_2O_3$/FeCrAl alloy foam for hydrogen production was prepared using atomic layer deposition (ALD) and subsequent dip-coating methods. FeCrAl alloy foam and $Al_2O_3$ inter-layer were used as catalyst supports. To improve the dispersion and stability of NiO catalysts, an $Al_2O_3$ inter-layer was introduced and their thickness was systematically controlled to 0, 20, 50 and 80 nm using an ALD technique. The structural, chemical bonding and morphological properties (including dispersion) of the NiO catalysts/$Al_2O_3$/FeCrAl alloy foam were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy and scanning electron microscopy-energy dispersive spectroscopy. In particular, to evaluate the stability of the NiO catalysts grown on $Al_2O_3$/FeCrAl alloy foam, chronoamperometry tests were performed and then the ingredient amounts of electrolytes were analyzed via inductively coupled plasma spectrometer. We found that the introduction of $Al_2O_3$ inter-layer improved the dispersion and stability of the NiO catalysts on the supports. Thus, when an $Al_2O_3$ inter-layer with a 80 nm thickness was grown between the FeCrAl alloy foam and the NiO catalysts, it indicated improved dispersion and stability of the NiO catalysts compared to the other samples. The performance improvement can be explained by optimum thickness of $Al_2O_3$ inter-layer resulting from the role of a passivation layer.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.105-105
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• 2012

We have developed a photoemission-assisted plasma-enhanced chemical vapor deposition (PAPE-CVD) [1,2], in which photoelectrons emitting from the substrate surface irradiated with UV light ($h{\nu}$=7.2 eV) from a Xe excimer lamp are utilized as a trigger for generating DC discharge plasma as depicted in Fig. 1. As a result, photoemission-assisted plasma can appear just above the substrate surface with a limited interval between the substrate and the electrode (~10 mm), enabling us to suppress effectively the unintended deposition of soot on the chamber walls, to increase the deposition rate, and to decrease drastically the electric power consumption. In case of the deposition of DLC gate insulator films for the top-gate graphene channel FET, plasma discharge power is reduced down to as low as 0.01W, giving rise to decrease significantly the plasma-induced damage on the graphene channel [3]. In addition, DLC thickness can be precisely controlled in an atomic scale and dielectric constant is also changed from low ${\kappa}$ for the passivation layer to high ${\kappa}$ for the gate insulator. On the other hand, negative electron affinity (NEA) of a hydrogen-terminated diamond surface is attractive and of practical importance for PAPECVD, because the diamond surface under PAPE-CVD with H2-diluted (about 1%) CH4 gas is exposed to a lot of hydrogen radicals and therefore can perform as a high-efficiency electron emitter due to NEA. In fact, we observed a large change of discharge current between with and without hydrogen termination. It is noted that photoelectrons are emitted from the SiO2 (350 nm)/Si interface with 7.2-eV UV light, making it possible to grow few-layer graphene on the thick SiO2 surface with no transition layer of amorphous carbon by means of PAPE-CVD without any metal catalyst.

• 한국진공학회지
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• 제22권6호
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• pp.335-340
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• 2013

본 논문은 InP 식각정지층을 갖는 MHEMT 소자의 항복전압을 증가시키기 위한 시뮬레이션 설계 논문이다. MHEMT 소자의 게이트 리세스 구조 및 채널 구조를 변경하여 시뮬레이션을 수행하였고 비교 분석하였다. MHEMT 소자의 드레인 측만을 완전히 제거한 비대칭 게이트 리세스 구조인 경우 $I_{dss}$ 전류가 90 mA에서 60 mA로 줄어들지만 항복 전압은 2 V에서 4 V로 증가함을 확인하였다. 이는 $Si_3N_4$ 보호층과 InAlAs 장벽층 사이의 계면에서 형성되는 전자-포획 음의 고정전하로 인해 채널층에서의 전자 공핍이 심화되어 나타나는 현상으로 이는 채널층의 전류를 감소시켜 충돌이온화를 적게 형성시켜 항복전압을 증가시킨다. 또한, 동일한 구조의 비대칭 게이트 리세스 구조에서 채널층을 InGaAs/InP 복합 채널로 바꾸어 설계한 구조에서는 항복전압이 5 V로 증가하였다. 이는 높은 드레인 전압에서 InP 층의 적은 충돌이온화와 이동도로 인해 전류가 더 감소했기 때문이다.

• 센서학회지
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• 제7권6호
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• pp.426-431
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• 1998

본 논문에서는 THAH/IPA/pyrazine 용액에서의 전기화학적 식각정지특성을 기술한다. THAH/IPA/pyrazine 용액에서의 n-형과 p-형의 Si에 대한 I-V 곡선이 얻어졌다. p-형 Si에 대한 OCP(개방회로전압)과 PP(보호막생성 전압)은 각각 -1.2 V와 0.1 V이고, n-형에 대해서는 -1.3 V와 -0.2 V로 각각 나타났다. p-형과 n-형 Si 모두 PP점보다 양의 전압에서 식각율이 급속히 감소하였다. 또한 THAH/IPA/pyrazine 용액에서의 식각정지특성을 관찰하였다. pn 접합부에서의 정확한 식각정지에 의해서 epi. 층의 두께에 상응하는 Si 다이어프램을 제작할 수 있었다. 최적 이방성 식각조건인 TMAH 25 wt.%/IPA 17 vol.%/pyrazine 0.1g/100ml에서 식각률이 가장 높기 때문에 식각소요시간이 크게 감소하였다.

• 한국표면공학회지
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• 제31권1호
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• pp.54-62
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• 1998

In this study, the behaviorof ion nitriding of AISI 304 stainless steel was investigated using plasma ion nitriding system. The characteristics of ion nitriding, and their micsoctrucyures, and physical properties were investigated as a function of process parmeteds. important conclusions can be summarzied as follows. Firstly, it was found that growth of nitride layer in ion nitriding are mainly affected by N2 partial pressures and nitriding temperatures for AISI 304 stainless steel. The $N_2$<\TEX> partial pressure plays on important role in ion nitriding since it determiness the incoming flux of nitrogen species onto specimen surface. Nitriding thmprrature is also important besauseit determines the diffusion rates of nitrogen through nitride layers. While both parameters affects the characteristics rateding are controlled by nitridingen diffusion nitration profiles of N and alloying elements such as Cr and Ni are observed through niride layers. Secondly, nitride layer consists of the upper white laywe having various nitride phases and the underneath diffusion layers. The thickness of white layer increases with $N_2$<\TEX> partial pressures and nitriding temperatures. The thinkness of diffusion layer is increasting nitriding temperatures. Finally, nitriding of stainless steels steel show slighly low their corrsionce prorerties. However, passivation properties, which is normally observed in stainless steels, were still observed aftre ion nitriding.

• 한국분말재료학회지
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• 제23권2호
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• pp.91-94
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• 2016

High-quality colloidal CdSe/ZnS (core/shell) is synthesized using a continuous microreactor. The particle size of the synthesized quantum dots (QDs) is a function of the precursor flow rate; as the precursor flow rate increases, the size of the QDs decreases and the band gap energy increases. The photoluminescence properties are found to depend strongly on the flow rate of the CdSe precursor owing to the change in the core size. In addition, a gradual shift in the maximum luminescent wave (${\lambda}_{max}$) to shorter wavelengths (blue shift) is found owing to the decrease in the QD size in accordance with the quantum confinement effect. The ZnS shell decreases the surface defect concentration of CdSe. It also lowers the thermal energy dissipation by increasing the concentration of recombination. Thus, a relatively high emission and quantum yield occur because of an increase in the optical energy emitted at equal concentration. In addition, the maximum quantum yield is derived for process conditions of 0.35 ml/min and is related to the optimum thickness of the shell material.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.55-55
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• 2018

Recently, amorphous oxides such as InGaZnO (IGZO) and InZnO (IZO) as a channel layer of an oxide TFT have been attracted by advantages such as high mobility, good uniformity, and high transparency. In order to apply such an amorphous oxide TFTs to a display, the stability in various environments must be ensured. In the InGaZnO which has been studied in the past, Ga elements act as a suppressor of oxygen vacancy and result in a decreased mobility at the same time. Previous studies have been showed that the InZnO, which does not contain Ga, can achieve high mobility, but has relatively poor stability under various instability environments. In this study, the TFTs using $IZO/Al_2O_3$ double layer structure were studied. The introduction of an $Al_2O_3$ interlayer between source/drain and channel causes superior electrical characteristics and electrical stability as well as reduced contact resistance with optimally perfect ohmic contact. For the IZO and $Al_2O_3$ bilayer structures, the IZO 30nm IZO channels were prepared at $Ar:O_2=30:1$ by sputtering and the $Al_2O_3$ interlayer were depostied with various thickness by ALD at $150^{\circ}C$. The optimal sample exhibits considerably good TFT performance with $V_{th}$ of -3.3V and field effect mobility of $19.25cm^2/Vs$, and reduced $V_{th}$ shift under positive bias stress stability, compared to conventional IZO TFT. The enhanced TFT performances are closely related to the nice ohmic contact properties coming from the defect passivation of the IZO surface inducing charge traps, and we will provide the detail mechanism and model via electrical analysis and transmission line method.