• Title, Summary, Keyword: Local oxidation

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Local Oxidation Characteristics on Implanted 4H-SiC by Atomic Force Microscopy (원자힘 현미경을 이용한 이온 주입된 4H-SiC 상의 국소 산화 특성)

  • Lee, Jung-Ho;Ahn, Jung-Joon;Koo, Sang-Mo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.4
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    • pp.294-297
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    • 2012
  • In this work, local oxidation behavior in phosphorous ion-implanted 4H-SiC has been investigated by using atomic force microscopy (AFM). The AFM-local oxidation (AFM-LO) has been performed on the implanted samples, with and without activation anneal, using an applied bias (~25 V). It has been clearly shown that the post-implantation annealing process at $1,650^{\circ}C$ has a great impact on the local oxidation rate by electrically activating the dopants and by modulating the surface roughness. In addition, the composition of resulting oxides changes depending on the doping level of SiC surfaces.

Humidity dependent size control of local anodic oxidation on graphene using Atomic Force Microscope (원자힘 현미경의 습도 조절에 의한 그래핀 국소 산화)

  • Ko, Seoknam;Lee, Seong jun;Son, Maengho;Ahn, Doyeol;Lee, Seung-Woong
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • pp.226-227
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    • 2014
  • We demonstrate nanoscale local anodic oxidation (LAO) patterning on few layer graphene using atomic force microscope (AFM) at room temperature and normal atmosphere. We focus on the humidity dependency in nanoscale oxidation of graphene. The relationship between the oxidation size and the AFM setting values, such as set point, tip speed, and humidity are observed. By changing these values, proper parameters were found to produce features on demand size. This technique provides an easy way to form graphene oxide lithography without any chemical resists. We have obtained oxidation size down to 50-nm with 6-nm-height oxide barrier line with $0.1{\mu}m/s$ tip scanning speed and micrometer size symbols on a graphene flake. We attribute the bumps to local anodic oxidation on graphene surface and combination of oxygen ions into the graphene lattice.

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Local oxidation of 4H-SiC using an atomic force microscopy (Atomic Force Microscopy을 이용한 4H-SiC의 Local Oxidation)

  • Jo, Yeong-Deuk;Bahng, Wook;Kim, Sang-Cheol;Kim, Nam-Kyun;Koo, Sang-Mo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.79-80
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    • 2009
  • The local oxidation using an atomic force microscopy (AFM) is useful for Si-base fabrication of nanoscale structures and devices. SiC is a wide band-gap material that has advantages such as high-power, high-temperature and high-frequency in applications, and among several SiC poly types, 4H-SiC is the most attractive poly type due to the high electron mobility. However, the AFM local oxidation of 4H-SiC for fabrication is still difficult, mainly due to the physical hardness and chemical inactivity of SiC. In this paper, we investigated the local oxidation of 4H-SiC surface using an AFM. We fabricated oxide patterns using a contact mode AFM with a Pt/Ir-coated Si tip (N-type, $0.01{\sim}0.025\;{\Omega}cm$) at room temperature, and the relative humidity ranged from 40 to 50%. The height of the fabricated oxide pattern ($1{\sim}3\;nm$) on SiC is similar to that of typically obtained on Si ($10^{15}{\sim}10^{17}\;cm^{-3}$). We perform the 2-D simulation to further analyze the electric field between the tip and the surface. Whereas the simulated electric field on Si surface is constant ($5\;{\times}\;10^7\;V/m$), the electric field on SiC surface increases with increasing the doping concentration from ${\sim}10^{15}$ to ${\sim}10^{17}\;cm^{-3}$. We demonstrated that a specific electric field ($4\;{\times}\;10^7\;V/m$) and a doping concentration (${\sim}10^{17}\;cm^{-3}$) is sufficient to switch on/off the growth of the local oxide on SiC.

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Local Oxidation of 4H-SiC using an Atomic Force Microscopy (원자현미경을 이용한 탄화규소 (SiC)의 국소산화)

  • Jo, Yeong-Deuk;Bahng, Wook;Kim, Sang-Cheol;Kim, Nam-Kyun;Koo, Sang-Mo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.22 no.8
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    • pp.632-636
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    • 2009
  • The local oxidation using an atomic force microscopy (AFM) is useful for Si-based fabrication of nanoscale structures and devices. SiC is a wide band-gap material that has advantages such as high-power, high-temperature and high-frequency in applications, and among several SiC polytypes, 4H-SiC is the most attractive polytype due to the high electron mobility. However, the AFM local oxidation of 4H-SiC for fabrication is still difficult, mainly due to the physical hardness and chemical inactivity of SiC. In this paper, we investigated the local oxidation of 4H-SiC surface using an AFM. We fabricated oxide patterns using a contact mode AFM with a Pt/Ir-coated Si tip (N-type, 0.01-0.025 ${\Omega}cm$) at room temperature, and the relative humidity ranged from 40 to 50 %. The height of the fabricated oxide pattern (1-3 nm) on SiC is similar to that of typically obtained on Si ($10^{15}^{\sim}10^{17}$ $cm^{-3}$). We perform the 2-D simulation to further analyze the electric field between the tip and the surface. We demonstrated that a specific electric field (4 ${\times}$ $10^7\;V/m$) and a doping concentration ($^{\sim}10^{17}$ $cm^{-3}$) is sufficient to switch on/off the growth of the local oxide on SiC.

Magnetoresistance of Planar Ferromagnetic Junction Defined by Atomic Force Microscopy

  • Yu, D.S.;Jerng, S.K.;Kim, Y.S.;Chun, S.H.
    • Journal of Magnetics
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    • v.14 no.4
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    • pp.172-174
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    • 2009
  • Nanolithography by atomic force microscope local oxidation was applied to the fabrication of planar-type Ni/Ni oxide/Ni junctions from 10 nm-thick Ni films. The junction characteristics were sensitive to the lithography conditions such as the bias voltage. Successful oxidation produced junctions of nonlinear current-voltage characteristics, implying the formation of oxide barriers. Magnetoresistance (MR) at low temperatures resembled that of spin valves.

Numerical simulation of the effects of localized cladding oxidation on LWR fuel rod design limits using a SLICE-DO model of the FALCON code

  • Khvostov, Grigori
    • Nuclear Engineering and Technology
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    • v.52 no.1
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    • pp.135-147
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    • 2020
  • A methodology for evaluation of mechanical and thermal effects of localized non-axisymmetric oxidation in zircaloy claddings on LWR fuel reliability is proposed. To this end, the basic capabilities of the FALCON fuel behaviour code are used. Examples of methodology application to adjustment of selected operational limits for modern BWR fuel rods, to capture effects of the excess local oxidation, are presented. Specifically, the limiting rod internal pressure for the onset of cladding lift-off is reduced, depending on initial excess oxidation spot sizes. Also, the power limits for Anticipated Operational Occurrences are adjusted, to preclude fuel melting and cladding failure due to PCMI and PCI-SCC in the affected fuel rods.

Local Current Distribution in a Ferromagnetic Tunnel Junction Fabricated Using Microwave Excited Plasma Method (마이크로파 여기 프라즈마법으로 제조한 강자성 터널링 접합의 국소전도특성)

  • Yoon, Tae-Sick;Kim, Cheol-Gi;Kim, Chong-Oh;Masakiyo Tsunoda;Migaku Takahashi;Ying Li
    • Journal of the Korean Magnetics Society
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    • v.13 no.2
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    • pp.47-52
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    • 2003
  • Ferromagnetic tunnel junctions were fabricated by dc magnetron sputtering and plasma oxidation process. The local transport properties of the ferromagnetic tunnel junctions were studied using contact-mode Atomic Force Microscopy (AFM) and the local current-voltage analysis. Tunnel junctions with the structure of sub./Ta/Cu/Ta/NiFe/Cu/Mn$\_$75/Ir$\_$25//Co$\_$70/Fe$\_$30//Al-oxide were prepared on thermally oxidized Si wafers. Al-oxide layers were formed with microwave excited plasma using radial line slot antenna (RLSA) for 5 and 7 sec. Kr gas was used as the inert gas mixed with $O_2$ gas for the plasma oxidization. No correlation between topography and current image was observed while they were measured simultaneously. The local current distribution was well identified with the distribution of local barrier height. Assuming the gaussian distribution of the local barrier height, the ferromagnetic tunnel junction with longer oxidation time was well fitted with the experimental results. As contrast, in the case of the shorter time oxidation junction, the current mainly flow through the low barrier height area for its insufficient oxygen. Such leakage current might result in the decrease of tunnel magnetoresistance (TMR) ratio.

Fabrication and characterization of SILO isolation structure (SILO 구조의 제작 방법과 소자 분리 특성)

  • Choi, Soo-Han;Jang, Tae-Kyong;Kim, Byeong-Yeol
    • Proceedings of the KIEE Conference
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    • pp.328-331
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    • 1988
  • Sealed Interface Local Oxidation (SILO) technology has been investigated using a nitride/oxide/nitride three-layered sandwich structure. P-type silicon substrate was either nitrided by rapid thermal processing, or silicon nitride was deposited by LPCVD method. A three-layered sandwich structure was patterned either by reactive ion etch (RIE) mode or by plasma mode. Sacrificial oxidation conditions were also varied. Physical characterization such as cross-section analysis of field oxide, and electrical characterization such as gate oxide integrity, junction leakage and transistor behavior were carried out. It was found that bird's beak was nearly zero or below 0.1um, and the junction leakages in plasma mode were low compared to devices of the same geometry patterned in RIE mode, and gate oxide integrity and transistor behavior were comparable. Conclusively, SILO process is compatible with conventional local oxidation process.

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Kinetics and Mechanistic Chemistry of Oxidation of Butacaine Sulfate by Chloramine-B in Acid Medium

  • Shubha, Jayachamarajapura Pranesh;Kotabagi, Vinutha;Puttaswamy, Puttaswamy
    • Bulletin of the Korean Chemical Society
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    • v.33 no.11
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    • pp.3539-3543
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    • 2012
  • Butacaine sulfate is an ester of p-aminobenzoic acid which has been widely used as a local anaesthetic and it is a long standing agent particularly for spinal anaesthesia. For this reason, a kinetic study of oxidation of butacaine sulfate by sodium N-chlorobenzenesulfonamide (chloramine-B or CAB) has been carried out in $HClO_4$ medium at 303 K in order to explore this redox system mechanistic chemistry. The rate shows a first-order dependence on both $[CAB]_o$, and $[substrate]_o$, and a fractional-order dependence on acid concentration. Decrease of dielectric constant of the medium, by adding methanol, increases the rate of the reaction. Variation of ionic strength and addition of benzenesulfonamide or NaCl have no significant effect on the rate. The reaction was studied at different temperatures and the activation parameters have been evaluated. The stoichiometry of the reaction has been found to be 1:2 and the oxidation products have been identified by spectral analysis. The observed results have been explained by plausible mechanism and the related rate law has been deduced.