• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.99-99
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• 2003

The growth of GaN on Si is of great interest due to the several advantages : low cost, large size and high-quality wafer availability as well as its matured technology. The crystal quality of GaN is known to be much influenced by the surface pretreatment of Si substrate[1]. In this work, the properties of GaN overlayer grown on ion beam modified Si(111) have been investigated. Si(111) surface was treated RIB with 1KeV-N$_2$$\^$+/(at 1.9 ${\times}$ 10$\^$-5/) to dose ranging from 5${\times}$10$\^$15/ to 1${\times}$10$\^$17/ prior to film growth. GaN epilayers were grown at 1100$^{\circ}C$ for 1 hour after growing AlN buffer layers for 5∼30 minutes at 1100$^{\circ}C$ in Metal Organic Chemical Vapor Deposition (MOCVD). The properties of GaN epilayers were evaluated by X-Ray Diffraction(XRD), Raman spectroscopy, Photoluminescence(PL) and Hall measurement. The results showed that the ion modified treatment markedly affected to the structural, optical and electrical characteristic of GaN layers.

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.2
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• pp.69-76
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• 2006

TRISO(tri-isotropic)-coated fuel particle technology is utilized owing to its higher stability at a high temperature and Its efficient retention capability for fission products In the HTGR(high temperature gas-reeled reactor). The typical spherical TRISO fuel panicle with a diameter of about 1mm is composed of a nuclear fuel kernel and outer coating layers. The outer coating layers consist of a buffer PyC(pyrolytic carbon) layer, Inner PyC(1-PyC) layer, SiC layer, and outer PyC(O-PyC) layer Most of the Inspection Items for the TRTSO-coated fuel particle depend on destructive methods. The coating thickness of the TRISO fuel particle can be nondestructively measured by the X-ray radiography without generating radioactive wastel. In this study, the coaling thickness for the simulated TRISO-coated fuel particle with $ZrO_2$ kernel Instead of $%UO_2$ kernel was measured by using micro-focus X-ray radiography with micro-focus X-ray generator and flat panel detector The radiographic image was also enhanced by image processing technique to acquire clear boundary lines between coating layers. The coaling thickness wat effectively measured by applying the micro-focus X-ray radiography The inspection process for the TRISO-coated fuel particles will be improved by the developed micro-focus X-ray radiography and digital image processing technology.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2002.11a
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• pp.10-13
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• 2002

본 논문에서는 P-type (100)Si 기판위에 RF magnetron sputtering법으로 강유전체 BST 박막을 증착하기 위한 완충층용(buffer layer) MgO 박막을 제작하였다. 증착 시 기판온도는 $400^{\circ}C$, 작업가스 Ar:$O_2$:=80:20, 작업진공 10m torr에서 RF 파워를 25W, 50W, 7SW로 변화하면서 증착하여 최적의 RF 파워조건을 확립하였다. XRD 측정결과 RF 파워 세기에 관계없이 MgO(200)피크만 관찰되었고 RF 파워 5OW에서 제작한 박막이 가장 양호한 결정성을 나타내었고 이 때 I-V측정결과 $\pm$ 1.5 MV/$cm^2$에서 $10^{-7}$A/$cm^2$이하의 양호한 누설전류특성을 나타내었고 C-V 측정결과 히스테리시스가 거의없는 양호한 인터페이스 특성을 보여주었고 비유전율은 약 8.4였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.5
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• pp.415-420
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• 2008

AAO films were fabricated on two kinds of substrates such as $Al/SiO_2/Si$ and Al/Ni/Ti/Si. To obtain well-aligned AAO film, we optimized process condition for buffer layer, electrolyte and voltage. In the case of oxalic acid, the AAO film with pore size of approximately 45 nm was obtained at voltage of 40 V, temperature of $10^{\circ}C$, oxalic acid of 0.3 M and widening time of 60 min. Then the thickness of barrier is less than 600 nm. In the case of sulfuric acid, the AAO film has pore size of 40 nm and barrier thickness of 400 nm with optimum conditions such as voltage of 25 V, temperature of $8^{\circ}C$, sulfuric acid of 0.3 M and widening time of 60 min.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.131-131
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• 2011

이종접합 태양전지 제작을 위해 기판의 buffer layer로 사용되는 기존의 a-Si 박막을 SiON 박막으로 대체하려는 연구가 진행 중이다. 기존의 a-Si 박막은 대면적에서 균일도를 담보하기 어렵고, 열적 안정성에 취약한 문제점이 있다. 이에 반해 SiON 박막은 일종의 화학 반응인 oxidation 방법으로 형성이 되기 때문에 막의 균일도를 담보 할 수 있고, $400^{\circ}C$이상의 온도에서 형성되기 때문에 열적 안정성이 우수한 장점이 있다. 이러한 장점에도 불구하고 기판위에 직접 형성이 되기 때문에 기판과 SiON 계면 사이의 pssivation이 무엇보다 중요하다. 본 연구에서는 비정질 실리콘 이종접합 태양전지에 적용키 위한 SiON 박막을 형성하고, 기판과 SiON 계면에서의 passivation 향상을 위한 계면 결함 감소에 대한 연구를 진행하였다. 실험을 위한 SiON 박막은 공정온도 $450^{\circ}C$, 공정압력 100 mTorr, 증착파워 120 mW/cm2에서 5분간 증착하였으며, 이때 50 sccm의 N2O 가스를 주입하였다. 증착된 박막은 2~4 nm의 두께로 증착이 되었으며, 1.46의 광학적 굴절률을 가지는 것으로 분석되었다. 계면의 결함을 줄이기 위해 PECVD를 이용한 NH3 plasma treatment를 실시하였다. 공정온도 $400^{\circ}C$, 공정압력 150mTorr~450 mTorr, 플라즈마 파워 60mW/cm2에서 30분간 진행하였으며, 50 sccm의 N2O 가스를 주입하였다. 계면의 결함이 줄었는지 확인하기 위해 C-V 측정을 위한 시료를 제작하여 분석을 하였다. 실험 결과 VFB가 NH3 plasma treatment 이후 positive 방향으로 shift 됨을 알 수 있었다. Dit 분석을 통해 공정 압력 450 mTorr에서 $4.66{\times}108$[cm2/eV]로 가장 낮은 계면 결함 밀도를 확인 할 수 있었다. 결과적으로 NH3 plasma 처리를 통해 positive charge를 갖는 N-content가 형성되었음을 예측해 볼 수 있으며, N-content가 증가하면, 조밀한 Si-N 결합을 형성하면서, boron 및 phosphorus diffusion을 막는데 효과적이다. 또한, plasma treatment 과정에서 H-content에 의한 passivation 효과를 기대할 수 있다.

• Transactions on Electrical and Electronic Materials
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• v.7 no.2
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• pp.67-71
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• 2006

In this paper, we have investigated the structure and dielectric properties of the $(Ba_{0.6}Sr_{0.4})TiO_3$ (BST) thin films fabricated on MgO(100)/Si substrate by an alkoxide-based sol-gel method. Both the structure and morphology of those films were analyzed by x-ray diffraction (XRD) and atomic force microscope (AFM). For the MgO(100)/Si substrate, the BST thin films exhibited highly (100) orientation. The highly (100)-oriented BST thin films showed high dielectric constant, tunability, and figure of merit (FOM). The dielectric constant, dielectric loss and tunability of the BST thin films annealed at $700^{\circ}C$ deposited on the MgO(100)/Si substrate measured at 10 kHz were 515.9, 0.0082, and 54.3%, respectively.

• KIEE International Transactions on Electrophysics and Applications
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• v.12C no.4
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• pp.208-213
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• 2002

The present study describe the electrical performance of amorphous T $a_2$ $O_{5-X}$ fabricated on the buffer layers Ti and Ti $O_2$. T $a_2$ $O_{5-X}$ thin films were grown on the Ti and Ti $O_2$ layers as a capacitor layer using reactive sputtering method. The X-ray pattern analysis indicated that the two as-deposited films were amorphous and the amorphous state was kept stable on the RTA(rapid thermal annealing) at even $700^{\circ}C$. Measurements of dielectric properties of the reactive sputtered T $a_2$ $O_{5-X}$ thin films fabricated in two simple MIS(metal insulator semiconductor), structures, (Cu/T $a_2$ $O_{5}$ Ti/Si and CuT $a_2$ $O_{5}$ Ti $O_2$Si) show that the amorphous T $a_2$ $O_{5}$ grown on Ti showed high dielectric constant (23～39) and high leakage current density(10$^{-3}$ ～10$^{-4}$ (A/$\textrm{cm}^2$)), whereas relatively low dielectric constant (～15) and tow leakage current density(10$^{-9}$ ～10$^{-10}$ (A/$\textrm{cm}^2$)) were observed in the amorphous T $a_2$ $O_{5}$ deposited on the Ti $O_2$ layer. The electrical behaviors of the T $a_2$ $O^{5}$ thin films were attributed to the contribution of Ti- $O_2$ and the compositionally gradient Ta-Ti-0, being the low dielectric layer and high leakage current barrier. In additional, The T $a_2$ $O_{5}$ Ti $O_2$ thin films exhibited dominant conduction mechanism contributed by the Poole-Frenkel emission at high electric field. In the case of T $a_2$ $O_{5}$ Ti $O_2$ thin films were related to the diffusion of Ta, Ti and O, followed by the creation of vacancies, in the rapid thermal treated thin films.films.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.1
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• pp.29-34
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• 2009

PLZT thin films were deposited on platinized silicon (Pt/$TiSiO_2$/Si) substrate by RF magnetron sputtering. A $TiO_2$ buffer layer was fabricated, prior to deposition of PLZT films. the layer was strongly affected the crystallographic orientation of the PLZT films. X-ray diffraction was performed on the films to study the crystallization of the films as various substrate temperatures (Ts). According to increasing Ts, preferred orientation of films was changed (110) plane to (111) plane. The ferroelectric, dielectric and electrical properties of the films were also investigated in detail as increased substrate temperatures. The PLZT films deposited at $400^{\circ}C$ showed good ferroelectric properties with the remnant polarization of $15.8{\mu}C/cm^2$ and leakage current of $5.4{\times}10^{-9}\;A/cm^2$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.2
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• pp.164-168
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• 2005

Piezoelectric ZnO thin films were for the first time formed on SiO$_2$/Si(100) substrate using 2-step deposition, atomic layer deposition(ALD) and RF magnetron sputtering deposition, for film bulk acoustic resonator(FBAR) applications. The ZnO buffer layer by ALD was deposited using alternating diethyl zinc(DEZn)/$H_2O$ exposures and ultrahigh purity argon gas for purging. The ZnO films by 2-step deposition revealed stronger c-axis-preferred orientation and smoother surface than those by the conventional RF sputtering method. The solidly mounted resonator(SMR)-typed FBAR fabricated by using 2-step deposition method revealed higher quality factor of 580 and lower return loss of -17.35dB. Therefore the 2-step deposition method in this study could be applied to the FBAR device fabrication.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.197-198
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• 2005

본 논문에서는 p-type (100)Si. (100)MgO 그리고 MgO/Si 기판 위에 RF Magnetron sputtering 법으로 $Ba_{0.5}Sr_{0.5}TiO_3$(BST) 박막을 증착 후 $600^{\circ}C$ 의 질소분위에서 RTA(Rapid Thermal Annealing)를 이용한 1 분간의 고온 급속열처리를 하였다. XRD 측정결과 모든 기판에서 (110) $Ba_{0.5}Sr_{0.5}TiO_3$의 주피크가 관찰되어졌고, 열처리 후 피크 세기가 증가함을 확인할 수 있었다. C-V 특성에서 각각의 기판에서 측정된 커패시턴스 값으로 계산된 유전율은 120(bare Si), 305(MgO/Si) 그리고 310(MgO)이었다. 누설 전류 특성에서는 150KV/cm이내의 인가전계에서 0.1$uA/cm^2$이하의 안정된 누설전류값을 보여주었다. 결론적으로 MgO 버퍼층을 이용한 기판이 BST 박막의 증착을 위한 기판으로써 효과적임을 알 수 있었다.