• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2009년도 제38회 동계학술대회 초록집
• /
• pp.70-70
• /
• 2010

일차원 나노구조를 갖는 재료는 크기효과 뿐만 아니라 단결정성, 일차원성으로 인해 새로운 물리적, 화학적 성질과 높은 표면적-부피비 등으로 인하여 많은 관심의 대상이 되고 있다. 일차원 나노구조 중에 특히 GaAs 나노와이어의 경우, 미래의 전자 소자 혹은 광자 소자로서의 잠재력 때문에 많은 연구가 이루어지고 있다. GaAs 나노와이어는 MOCVD(Metal-Organic Chemical Vapor Deposition), CBE(Chemical Beam Epitaxy), MBE(Molecular Beam Epitaxy)등의 방법으로 성장시킬 수 있다. 본 연구에서는 아크 방전법으로 합성한 단일벽 탄소나노튜브 템플릿 위에 GaAs를 MBE로 성장시켜 다공성의 GaAs-탄소나노튜브 복합체를 제작하였다. GaAs는 성장온도를 $400^{\circ}{\sim}600^{\circ}C$ 사이로 변화시켜 성장시켰다. 성장온도가 $500^{\circ}C$ 미만일 경우에는 GaAs가 탄소나노튜브 위에서 입상구조로 성장이 되었으며 $500^{\circ}C$ 이상에서는 탄소나노튜브 위에 나노와이어가 성장되었다. 또한, 제작된 GaAs-탄소나노튜브 복합체를 전자 소스로서의 응용가능성을 보기 위해 전계 방출 특성을 측정하였다.

• 한국초전도ㆍ저온공학회논문지
• /
• 제4권2호
• /
• pp.5-10
• /
• 2002

Deposition condition of NiO that is one of Possible buffer layers for YBCO coated conductors was studied. NiO was deposited on textured Ni substrates by a MOCVD (metal-organic chemical vapor deposition) method. The degree of texture, and the surface roughness were analyzed by X-ray Pole figure, atomic force microscope and scanning electron microscope. The (111) and (200) textures were competitively developed , depending on an oxygen partial Pressure(PO2) and deposition temperature (Tp). The (200) textured NiO layer was deposited at Tp=450~47$0^{\circ}C$ and PO2= 1.67 Torr Out-of-Plane ($\omega$-scan) and in-plane ($\Phi$-scan) textures of the (200) NiO films were as good as 10.34$^{\circ}$ and 10.00$^{\circ}$ respectively The AFM surface roughness of NiO was in the range of 3~4.5 nm at PO2=0.91~3.34 Torr and at Tp=47$0^{\circ}C$ , and in the range of 3~13 nm at TP=450~53$0^{\circ}C$ and at PO2=1.67 Torr.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
• /
• pp.254-254
• /
• 2016

Tin dioxide (SnO2) thin film is one of the most important n-type semiconducting materials having a high transparency and chemical stability. Due to their favorable properties, it has been widely used as a base materials in the transparent conducting substrates, gas sensors, and other various electronic applications. Up to now, SnO2 thin film has been extensively studied by a various deposition techniques such as RF magnetron sputtering, sol-gel process, a solution process, pulsed laser deposition (PLD), chemical vapor deposition (CVD), and atomic layer deposition (ALD) [1-6]. Among them, ALD or plasma-enhanced ALD (PEALD) has recently been focused in diverse applications due to its inherent capability for nanotechnologies. SnO2 thin films can be prepared by ALD or PEALD using halide precursors or using various metal-organic (MO) precursors. In the literature, there are many reports on the ALD and PEALD processes for depositing SnO2 thin films using MO precursors [7-8]. However, only ALD-SnO2 processes has been reported for halide precursors and PEALD-SnO2 process has not been reported yet. Herein, therefore, we report the first PEALD process of SnO2 thin films using SnCl4 and oxygen plasma. In this work, the growth kinetics of PEALD-SnO2 as well as their physical and chemical properties were systemically investigated. Moreover, some promising applications of this process will be shown at the end of presentation.

• Progress in Superconductivity
• /
• 제7권1호
• /
• pp.69-76
• /
• 2005

Complex single buffer composed of yttrium and samarium oxide was deposited on the metallic substrates by MOCVD (metal organic chemical vapor deposition) method using single liquid source. Two different types of the substrates with in-plane textures of about $8{\sim}10$ degree of Ni and $3at.\%W-Ni$ alloy were used. Y(tmhd: 2,2,6,6-tetramethyl-3,5-heptane dionate)$_3$:Sm(tmhd)$_3$ of liquid source was adjusted to 0.4:0.6 to minimize the lattice mismatch between the complex single buffer and the YBCO. The epitaxial growth of $(Y_{x}Sm_{1-x})_{2}O_3$ was achieved at the temperature higher than $500^{\circ}C$ in $O_2$ atmosphere. However, it was found that the formation of NiO accelerated with increasing deposition temperature. By supplying $H_{2}O$ vapor, this oxidation of the substrate could be suppressed throughout the deposition temperatures. We could get the epitaxial growth on pure Ni substrate without the formation of NiO. The competitive (222) and (400) growths were observed at the deposition temperatures of $650\~750^{\circ}C$, but the (400) growth became dominant above $800^{\circ}C$. The $(Y_{x}Sm_{1-x})_{2}O_3$-buffered metallic substrates can be used as the buffer for YBCO coated conductor.

• 한국재료학회지
• /
• 제13권12호
• /
• pp.801-805
• /
• 2003

To explore the annealing temperature dependence of dielectric properties $Ta_2$$O_{5}$ thin films were prepared by MOCVD(metal-organic chemical vapor deposition) and MOD(metal-organic decomposition). The $Ta_2$$O_{5}$thin films fabricated MOCVD and MOD were annealed in $O_2$at temperature between 600 and 90$0^{\circ}C$. The measured dielectric constant of both films at 100 KHz was the highest value at $650^{\circ}C$ and decreased with increasing annealing temperature above $650^{\circ}C$. Plane-view SEM image showed that the boundary seems to be crack broke out with increasing annealing temperature. It was confirmed that outbreak of boundary influenced a decrease of dielectric constant with increasing annealing temperature. The leakage current density increased with increasing annealing temperature.

• Progress in Superconductivity
• /
• 제8권1호
• /
• pp.27-32
• /
• 2006

[$YBa_2Cu_3O_{7-x}$] thin films were deposited on various buffered-templates by a metal organic chemical vapor deposition(MOCVD). Three different templates of $CeO_2/YSZ/CeO_2/pure-Ni(CYC),\;CeO_2/YSZ/Y_2O_3/Ni-3at.%W(YYC)$ and $CeO_2/IBAD-YSZ$/stainless steel were used. The Ni and Ni-W alloy tapes were biaxially textured by cold rolling and annealing heat treatment. The dense YBCO films were grown on both the IBAD and YYC templates with no microcrack, while the YBCO films on the CYC templates were grown with the formation of microcracks and NiO. The YBCO film on the YYC template showed the higher $I_c$ than that on CYC template. Especially, the IBAD templates with a thin $CeO_2$(type I) and thick $CeO_2$(type II) top layer were used to compare the deposition nature of the YBCO on them. Comparing the current property of the YBCO films on IBAD templates, the YBCO film deposited on thick $CeO_2$ layer was better than the film on thin $CeO_2$ layer.

• 한국재료학회지
• /
• 제13권5호
• /
• pp.309-312
• /
• 2003

Tin dioxide($_SnO2$) thin films were deposited on alumina substrate by metal-organic chemical vapor deposition (MOCVD) as a function of temperature and time. Thin films were fabricated from di-n-butyltin diacetate as a precursor and oxygen as an oxidation. The microstructure of deposited films was characterized by X-ray diffraction and field emission scanning electron microscopy(FE-SEM). The thickness was linearly increased with deposition time and $SnO_2$structure was found from $375^{\circ}C$ for the deposition time of 32 min. The maximum sensitivity to 500ppm CO gas was observed for the specimens deposited at $375^{\circ}C$ for 2 min at the operating temperature of $350^{\circ}C$. Gas sensitivity to CO increased with decreasing the film thickness. The sensing properties of response time, recovery and sensitivity of CO were changed with variations of substrate temperature and time.

• 한국결정성장학회지
• /
• 제11권3호
• /
• pp.111-114
• /
• 2001

초음파분무를 이용한 MOCVD법으로 전도성 산화물 (Ba,Sr)RuO$_3$ 박막을 Si(100) wafer위에 제조하였다. XRD 측정 결과 BSR박막은 (110) 배향성을 가지고 성장하였으며 500$^{\circ}C$ 이상의 증착온도에서 결정성장이 양호하였다. Ba과 Sr의 조성비의 차이에 따라 AFM 측정결과 Ba에 대한 Sr의 비가 증가함에 따라 grain크기가 증가하였다. 또한 비저항의 측정을 통해 Ba에 대해 Sr의 비의 증가에 따라 BSR 박막의 비저항이 415에서 261$\mu$$\Omega$${\cdot}$cm로 감소하였다.

• 한국결정성장학회지
• /
• 제10권3호
• /
• pp.205-210
• /
• 2000

초음파분무를 이용한 MOCVD법으로 강유전체 $PbTiO_3$박막을 Si(100) wafer와 ITO-coated glass위에 제조하였다 Si 기판 위에 증착된 박막으로부터, 출발원료의 농도비(Ti/Pb)가 1.2일 때, 단일 perovskite 상을 얻을 수 있었다. ITO-coated glass 위에 증착된 박막은 Si기판 위에 제조된 박막보다 박막의 성장속도가 더 빠르며, 기판온도를 $530^{\circ}C$부터 $570^{\circ}C$까지 증가시켰을 때, 결절성과 입자 크기의 증가에 의해 유전상수는 증가하였다. $570^{\circ}C$에서의 유전상수 및 유전손실 값은 각각 205, 0.016을 나타내었다. 기판온도가 $600^{\circ}C$ 이상인 경우, 유전상수가 감소되는 경향을 보였다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2010년도 제39회 하계학술대회 초록집
• /
• pp.207-207
• /
• 2010

Both ZnO and GaN have excellent physical properties in optoelectronic devices such as blue light emitting diode (LED), blue laser diode (LD), and ultra-violet (UV) detector. The ZnO/GaN heterostructure, which has a potential to achieve the cost efficient LED technology, has been fabricated by using radio frequency (RF) sputtering, pyrolysis, metal organic chemical vapor deposition (MOCVD), direct current (DC) arc plasmatron, and pulsed laser deposition (PLD) methods. Among them, the PLD system has a benefit to control the composition ratio of the grown film from the mixture target. A 500-nm-thick ZnO film was grown by PLD technique on c-plane GaN/sapphire substrates. The post annealing process was executed at some varied temperature between from $300^{\circ}C$ to $900^{\circ}C$. The morphology and crystal structural properties obtained by using atomic force microscope (AFM) and x-ray diffraction (XRD) showed that the crystal quality of ZnO thin films can be improved as increasing the annealing temperature. We will discuss the post-treatment effect on film quality (uniformity and reliability) of ZnO/GaN heterostructures.