• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.234.2-234.2
• /
• 2014

Organic light emitting diode (OLED) is considered as the next generation flat panel displays due to its advantages of low power consumption, fast response time, broad viewing angle and flexibility. For the flexible application, it is essential to develop thin film encapsulation (TFE) to protect oxidation of organic materials from oxidative species such as oxygen and water vapor [1]. In many TFE research, the inorganic film by atomic layer deposition (ALD) process demonstrated a good barrier property. However, extremely low throughput of ALD process is considered as a major weakness for industrial application. Recently, there has been developed a high throughput ALD, called 'spatial ALD' [2]. In spatial ALD, the precursors and reactant gases are supplied continuously in same chamber, but they are separated physically using a purge gas streams to prevent mixing of the precursors and reactant gases. In this study, the $Al_2O_3$ thin film was deposited by spatial ALD process. We characterized various process variables in the spatial ALD such as temperature, scanning speed, and chemical compositions. Water vapor transmission rate (WVTR) was determined by calcium resistance test and less than $10-^3g/m^2{\cdot}day$ was achieved. The samples were analyzed by x-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscope (FE-SEM).

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.384.2-384.2
• /
• 2014

We investigated the electrical and structural properties of chemical vapor deposition (CVD)-grown graphene and post treated by O2 plasma. For the patterning of graphene, the plasma technology is generally used and essential for etching of graphene. But, the cautious O2 plasma treatments are required to avoid the damage in graphene edge which can be the harmful effects on the device performance. To analyze the effects of plasma treatment on structural properties of graphene, the change of surface morphology of graphene are measured by scanning electron microscope and atomic force microscope before and after plasma treatment. In addition, the binding energy of carbon and oxygen are measured through to X-ray photoelectron spectroscopy. After plasma treatment, the severe changes of surface morphology and binding energy of carbon and oxygen were observed which effects on the change of sheet resistance. Finally, to analyze of graphene characteristics, we measured the Raman spectroscopy. The measured results showed that the plasma treatment makes the upward of D-peak and downward of G'-peak by elevated power of plasma.

• Journal of Information Display
• /
• v.10 no.4
• /
• pp.137-142
• /
• 2009

Transparent top-gate Al-Zn-Sn-O (AZTO) thin-film transistors (TFTs) with an $Al_2O_3$ protective layer (PL) on an active layer were studied, and a transparent 2.5-inch QCIF+AMOLED (active-matrix organic light-emitting diode) display panel was fabricated using an AZTO TFT backplane. The AZTO active layers were deposited via RF magnetron sputtering at room temperature, and the PL was deposited via two different atomic-layer deposition (ALD) processes. The mobility and subthreshold slope were superior in the TFTs annealed in vacuum and with oxygen plasma PLs compared to the TFTs annealed in $O_2$ and with water vapor PLs, but the bias stability of the TFTs annealed in $O_2$ and with water vapor PLs was excellent.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.564-564
• /
• 2012

Graphene has been emerged as a fascinating material for future nanoelectronic applications due to its extraordinally electronic properties. However, their zero-bandgap semimetallic nature is a major problem for applications in high performance field-effect transistors (FETs). Graphene nanoribbons (GNRs) with narrow widths (${\geq}10nm$) exhibit semiconducting behavior, which can be used to overcome this problem. In previous reports, GNRs were produced by several approaches, such as electron beam lithography patterning, chemically derived GNRs, longitudinal unzipping of carbon nanotubes, and inorganic nanowire template. Using these methods, however, the width distribution of GNRs was a quiet broad and substantial defects were inevitably occurred. Here, we report a novel approach for fabricating width-tailored GNRs by focused ion beam-assisted chemical vapor deposition (FIB-CVD). Width-tailored phenanthrene ($C_{14}H_{10}$) templates for direct growth of GNRs were prepared on $SiO_2$/Si substrate by FIB-CVD. The GNRs on the templates were synthesized at $900-1,050^{\circ}C$ with introducing $CH_4$ $(20sccm)/H_2$ (10 sccm) mixture gas for 10-300 min. Structural characterizations of the GNRs were carried out using Raman spectroscopy, scanning electron microscopy, and atomic force microscopy.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.309-309
• /
• 2012

Heteroepitaxial growth remains as one of the continuously growing interests, because the heterogeneous crystallization on different substrates is a common feature in the fabrication processes of many semiconductor materials and devices, such as molecular beam epitaxy, pulsed laser deposition, sputtering, chemical bath deposition, chemical vapor deposition, hydrothermal synthesis, vapor phase transport and so on [1,2]. By using the R.F. sputtering system, ZnO thin films were deposited on graphene 4 and 6 mono layers, which is grown on 400 nm and 600 nm $SiO_2$ substrates, respectively. The ZnO thin layer was deposited at various temperatures by using a ZnO target. In this experimental, the working power and pressure were $3{\times}10^{-3}$ Torr and 50 W, respectively. The base pressure of the chamber was kept at a pressure around $10^{-6}$ Torr by using a turbo molecular pump. The oxygen and argon gas flows were controlled around 5 and 10 sccm by using a mass flow controller system, respectively. The structural properties of the samples were analyzed by XRD measurement. The film surface and carrier concentration were analyzed by an atomic force microscope and Hall measurement system. The surface morphologies were observed using field emission scanning electron microscope (FE-SEM).

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.121-122
• /
• 2011

광도파로 기반 센서의 성능을 개선시키기 위해서는 코어와 클래딩 층의 굴절률 차를 크게 하여 표면감도를 향상시켜야 한다. 이를 위해 센서용 광도파로 코어 층을 위한 고굴절률 SiNx 박막을 플라즈마 화학기상증착(PECVD, plasma enhanced chemical vapor deposition)법을 이용하여 성장한 후 그 표면특성을 분석하였다. 이 때 플라즈마 화학기상증착 공정 조건 중 NH3 가스를 제외하여 Si 성분이 많은 고굴절률 SiNx 박막의 성장을 유도하고 He/SiH4 가스유량비를 0에서 100까지 변화시켜 SiNx 박막의 표면거칠기를 제어하였다. Si기판 위에 SiNx 박막을 10분 성장 후 BOE(buffered oxide etchant)로 선택식각하여 그 박막두께를 alpha step으로 측정하는 방법으로 He/SiH4 가스유량비 조건별 박막성장률을 계산하였다. 그 결과 He/SiH4 가스유량비 증가함에 따라 박막성장률이 33 nm/min에서 19 nm/min으로 선형적인 감소함을 알 수 있었다. 박막두께가 190 nm가 되도록 He/SiH4 가스유량비 조건별 SiNx 박막을 성장한 후 그 표면특성을 AFM (atomic force microscope)으로 관찰하였다. 이를 통해 He/SiH4 가스유량비가 50일 때 SiNx 박막의 표면거칠기가 최소가 됨을 알 수 있었다.

• Progress in Superconductivity and Cryogenics
• /
• v.4 no.2
• /
• pp.21-26
• /
• 2002

Textured CeO2 buffer layers for YBCO coated conductors were deposited on biaxially textured Ni substrate by metalorganic chemical vapor deposition (MOCVD). The degree of texture of deposited $CeO_2$ films was strong1y dependent on the deposition temperature (Td) and oxygen Partial Pressure(PO2). ($\ell$00) textured $CeO_2$ films were well deposited at T=500~52$0^{\circ}C$. PO2=0.90~3.33 Torr. The surface morphology showed that the films consisted of columnar CeO2 films grown from the Ni substrates. The root mean square roughness of CeO$_2$ films estimated by atomic force microscopy(AFM) increased as the deposition temperature(Td) increa- sed. The growth rate of the $CeO_2$ films deposited at T=52$0^{\circ}C$ and PO2=2.30 Torr was 150~200 nm/min that was much faster than that of other Physical deposition methods.

• Current Optics and Photonics
• /
• v.1 no.4
• /
• pp.358-363
• /
• 2017

In this study, we present a detailed investigation of luminescence properties of a blue light-emitting diode using InGaN/GaN (indium component is 17.43%) multiple quantum wells as the active region grown on patterned sapphire substrate by low-pressure metal-organic chemical vapor deposition (MOCVD). High-resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), Raman scattering (RS) and photoluminescence (PL) measurements are employed to study the crystal quality, the threading dislocation density, surface morphology, residual strain existing in the active region and optical properties. We conclude that the crystalline quality and surface morphology can be greatly improved, the red-shift of peak wavelength is eliminated and the superior blue light LED can be obtained because the residual strain that existed in the active region can be relaxed when the LED is grown on patterned sapphire substrate (PSS). We discuss the mechanisms of growing on PSS to enhance the superior luminescence properties of blue light LED from the viewpoint of residual strain in the active region.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.4
• /
• pp.533-537
• /
• 2007

This paper describes the heteroepitaxial growth of single-crystalline 3C-SiC (cubic silicon carbide) thin films on Si (100) wafers by atmospheric pressure chemical vapor deposition (APCVD) at 1350 oC for micro/nanoelectromechanical system (M/NEMS) applications, in which hexamethyldisilane (HMDS, Si2(CH3)6) was used as a safe organosilane single-source precursor. The HMDS flow rate was 0.5 sccm and the H2 carrier gas flow rate was 2.5 slm. The HMDS flow rate was important in obtaing a mirror-like crystalline surface. The growth rate of the 3C-SiC film in this work was 4.3 μm/h. A 3C-SiC epitaxial film grown on the Si (100) substrate was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), reflection high energy electron diffraction (RHEED), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and Raman scattering, respectively. These results show that the main chemical components of the grown film were single-crystalline 3C-SiC layers. The 3C-SiC film had a very good crystal quality without twins, defects or dislocations, and a very low residual stress.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.7
• /
• pp.1349-1352
• /
• 2008

We report a novel patterning method for a homo-polymeric poly(3-hexylthiophene) (P3HT) nanofilm particularly capable of strong adhesion to a $SiO_2$ surface. An oxidized silicon wafer substrate was micro-contact printed with n-octadecyltrichlorosilane (OTS) monolayer, and subsequently its negative pattern was selfassembled with three different amino-functionalized alkylsilanes, (3-aminopropyl)trimethoxysilane (APS), N- (2-aminoethyl)-3-aminopropyltrimethoxy silane (EDAS), and (3-trimethoxysilylpropyl) diethylenetriamine (DETAS). Then, P3HT nanofilms were selectively grown on the aminosilane pre-patterned areas via the vapor phase polymerization method. To evaluate the adhesion, patterning, and the film itself, the PEDOT nanofilms and SAMs were investigated with a $Scotch^{(R)}$ tape test, contact angle analyzer, ATR-FT-IR, and optical and atomic force microscopes. The evaluation showed that the newly developed all bottom-up process can offer a simple and inexpensive patterning method for P3HT nanofilms robustly adhered to an oxidized Si wafer surface by the mediation of $FeCl_3$ and amino-functionalized alkylsilane SAMs.