• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.222-222
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• 2011

Titanium dioxide (TiO2) has a number of applications in optics and electronics due to its superior properties, such as physical and chemical stability, high refractive index, good transmission in vis and NIR regions, and high dielectric constant. Atomic layer deposition (ALD), also called atomic layer epitaxy, can be regarded as a special modification of the chemical vapor deposition method. ALD is a pulsed method in which the reactant vapors are alternately supplied onto the substrate. During each pulse, the precursors chemisorb or react with the surface groups. When the process conditions are suitably chosen, the film growth proceeds by alternate saturative surface reactions and is thus self-limiting. This makes it possible to cover even complex shaped objects with a uniform film. It is also possible to control the film thickness accurately simply by controlling the number of pulsing cycles repeated. We have investigated the ALD of TiO2 at 100$^{\circ}C$ using precursors titanium tetra-isopropoxide (TTIP) and H2O on -O, -OH terminated Si surface by in situ X-ray photoemission spectroscopy. ALD reactions with TTIP were performed on the H2O-dosed Si substrate at 100$^{\circ}C$, where one cycle was completed. The number of ALD cycles was increased by repeated deposition of H2O and TTIP at 100$^{\circ}C$. After precursor exposure, the samples were transferred under vacuum from the reaction chamber to the UHV chamber at room temperature for in situ XPS analysis. The XPS instrument included a hemispherical analyzer (ALPHA 110) and a monochromatic X-ray source generated by exciting Al K${\alpha}$ radiation (h${\nu}$=1486.6 eV).

• 반도체디스플레이기술학회지
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• 제21권1호
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• pp.67-70
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• 2022

In order to prevent water vapor and oxygen permeation in the organic light emitting diodes (OLED), Al₂O₃ thin-film encapsulation (TFE) technology were investigated. Atomic layer deposition (ALD) method was used for making the Al₂O₃ TFE layer because it has superior barrier performance with advantages of excellent uniformity over large scales at relatively low deposition temperatures. In this study, the thickness of the Al₂O₃ layer was varied by controlling the numbers of the unit pulse cycle including Tri Methyl Aluminum(Al(CH₃)₃) injection, Ar purge, and H₂O injection. In this case, several process parameters such as injection pulse times, Ar flow rate, precursor temperature, and substrate temperatures were fixed for analysis of the effect only on the thickness of the Al₂O₃ layer. As results, at least the thickness of 39 nm was required in order to obtain the minimum WVTR of 9.04 mg/m²day per one Al₂O₃ layer and a good transmittance of 90.94 % at 550 nm wavelength.

• 한국전기전자재료학회논문지
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• 제11권4호
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• pp.334-339
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• 1998

$Bi_2Sr_2CuO_x$(Bi-2201) thin films have been fabricated by atomic layer-by-layer deposition using ion beam sputtering (IBS) method. During the deposition, 14 wt%-ozone/oxygen mixture gas of typical pressure of $5.0\times10^{-5}$ Torr is supplied with ultraviolent light irradiation for oxidation. XRD and RHEED investigations reveal that a buffer layer with compositions different from Bi-2201 is formed at the early deposition stage of less than 10 units cell and then Bi-2201 oriented along the c-axis is grown.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권4호
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• pp.159-163
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• 2003

ln this work, we studied electrical characteristics and leakage current mechanism of $Ta_2O_{5}$ MOS(Metal-Oxide-Semiconductor) devices. $Ta_2O_{5}$ thin film (63 nm) was deposited by ALD(Atomic Layer Deposition) method at temperature of 235 $^{\circ}C$. The structures of the $Ta_2O_{5}$ thin films were examined by XRD(X-Ray Diffraction). From XRD, it is found that the structure of $Ta_2O_{5}$ is single phase and orthorhombic. From capacitance-voltage (C-V) anaysis, the dielectric constant was 19.4. The temperature dependence of current density-electric field (J-E) characteristics of $Ta_2O_{5}$ thin film was studied at temperature range of 300 - 423 K. In ohmic region (<0.5 MV/cm), the resistivity was 2.456${\times}10^{14}$ ($\omega{\cdot}cm$ at 348 K. The Schottky emission is dominant at lower temperature range from 300 to 323 K and Poole-Frenkel emission is dominant at higher temperature range from 348 to 423 K.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 일렉트렛트 및 응용기술
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• pp.41-46
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• 2002

In this work, we studied electrical characteristics and leakage current mechanism of Au/$Ta_2O_5$/Si metal-oxide-semiconductor (MOS) devices. $Ta_2O_5$ thin film (63nm) was deposited by atomic layer deposition (ALD) method at temperature of $235^{\circ}C$. The structures of the $Ta_2O_5$ thin films were examined by X-Ray Diffraction (XRD). From XRD, the structure of $Ta_2O_5$ was single phase and orthorhombic. From capacitance-voltage (C-V) analysis, the dielectric constant was 19.4. The temperature dependence of current-voltage (I-V) characteristics of $Ta_2O_5$ thin film was studied from 300 to 423 K. In ohmic region (<0.5 MVcm${-1}$), the resistivity was $2.4056{\times}10^{14}({\Omega}cm)$ at 348 K. The Schottky emission is dominant in lower temperature range from 300 to 323 K and Poole-Frenkel emission dominant in higher temperature range from 348 to 423 K.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.310.2-310.2
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• 2013

For enhancement of dye-sensitized solar cell performance, TiO2 blocking layer has been used to prevent recombination between electron and hole at the conducting oxide and electrolyte interface. In solid state dye-sensitized solar cells, it is necessary to fabricate pin-hole free TiO2 blocking layer. In this work, we deposited the TiO2 blocking layer on conducting oxide by atomic layer deposition and compared the efficiency. To compare the efficiency, we fabricate solid state dye-sensitized solar cell with using CuSCN as hole transport material. We see the efficiency improve with 40nm TiO2 blocking layer and the TiO2 blocking layer morphology was characterized by SEM. Also, we used this blocking layer in TiO2/Sb2S3/ CuSCN solar cell.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.259-260
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• 2006

$Bi_2Sr_2Ca_{n-1}Cu_nO_x$ superconducting thin films have been fabricated by atomic layer-by-layer deposition using IBS(Ion Beam Sputtering) method During the deposition, 90 mol% ozone gas of typical pressure of $1{\sim}9{\times}10^{-5}$ T orr are supplied with ultraviolet light irradiation for oxidation. XRD and RHEED investigations reveal out that a buffer layer with some different compositions is formed at the early deposition stage of less than 10 units cell and then Bi-2201 oriented along the c-axis is grown.

• 반도체디스플레이기술학회지
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• 제17권3호
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• pp.41-45
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• 2018

Two-dimensional (2D) materials have been studied extensively due to their excellent physical, chemical, and electrical properties. Among them, we report the material and device characteristics of tin disulfide ($SnS_2$). To apply $SnS_2$ as a channel layer in a transistor, $SnS_2$ channels were formed by a stripping method and a transfer method. The limitation of this method is that it is difficult to produce uniform device characteristics over a large area. Therefore, we directly deposited $SnS_2$ by atomic layer deposition (ALD) and then performed lithography. This method was able to produce devices with repeatable characteristics over a large area. However, the $SnS_2$ film was damaged by the acetone used as a photoresist (PR) developer during the lithography process, with the electrical properties of mobility of $2.6{\times}10^{-4}cm^2/Vs$, S.S. of 58.1 V/decade, and on/off current ratio of $1.8{\times}10^2$. These results are not suitable for advanced electronic devices. In this study, we analyzed the effect of acetone on $SnS_2$ and studied the device process to prevent such damage. Using polyvinyl alcohol (PVA) as a passivation layer during the lithography process, the electrical characteristics of the $SnS_2$ transistor had $2.11{\times}10^{-3}cm^2/Vs$ of mobility, 11.3 V/decade of S.S, and $2.5{\times}10^3$ of the on/off current ratio, which were 10x improvements to the $SnS_2$ transistor fabricated by the conventional method.

• 한국재료학회지
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• 제29권9호
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• pp.567-577
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• 2019

Aluminum nitride (AlN) has versatile and intriguing properties, such as wide direct bandgap, high thermal conductivity, good thermal and chemical stability, and various functionalities. Due to these properties, AlN thin films have been applied in various fields. However, AlN thin films are usually deposited by high temperature processes like chemical vapor deposition. To further enlarge the application of AlN films, atomic layer deposition (ALD) has been studied as a method of AlN thin film deposition at low temperature. In this mini review paper, we summarize the results of recent studies on AlN film grown by thermal and plasma enhanced ALD in terms of processing temperature, precursor type, reactant gas, and plasma source. Thermal ALD can grow AlN thin films at a wafer temperature of $150{\sim}550^{\circ}C$ with alkyl/amine or chloride precursors. Due to the low reactivity with $NH_3$ reactant gas, relatively high growth temperature and narrow window are reported. On the other hand, PEALD has an advantage of low temperature process, while crystallinity and defect level in the film are dependent on the plasma source. Lastly, we also introduce examples of application of ALD-grown AlN films in electronics.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.77-80
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• 1999

Bi$_2$Sr$_2$CuO$\sub$x/ thin films have been fabricated by atomic layer-by-layer deposition using ion beam sputtering(IBS) method. XRD and RHEED investigations reveal that a buffer layer with compositions different from Bi-2201 is formed at the early deposition stage of less than 10 units cell and then Bi-2201 oriented along the c-axis is grown.