• Title, Summary, Keyword: Oxygen partial pressure

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Electrical Conductivity of a $TiO_2$ Thin Film Deposited on $Al_2O_3$ Substrates by CVD

  • Hwang, Cheol-Seong;Kim, Hyeong-Joon
    • The Korean Journal of Ceramics
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    • v.1 no.1
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    • pp.21-28
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    • 1995
  • Electrical conductivity of $TiO_2$ thin films, deposited on $Al_2O_3$ substrates by metal organic chemical vapor deposition (MOCVD), was measured by four-point probe method in a temperature range from $800^{\circ}C$ to $1025^{\circ}C$ and an oxygen partial pressure range from $2.7{\times}10^{-5}$ atm to 1 atm. In the low oxygen partial pressure region n-type conduction was dominant, but in the high oxygen partial pressure region p-type conduction behavior appeared due to substitution of Ti ions by Al ions, which were diffused from the substrate during post deposition annealing process. Electrical conductivity of the film decreases in the n-type region and increases in the p-type region as the oxygen partial pressure increases. The transition points, which show the minimum conductivity, shifted to the higher oxygen partial pressure region as the measuring temperature increased, but it shifted to lower oxygen partial pressure region with an increase in the post annealing temperature. The results were also discussed with the possible defect models.

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Thermal Stability of Superconductor NdBCO Sintered at Various Oxygen Partial Pressures (다양한 산소분압에서 소결한 NdBCO 초전도체의 열적 안정성)

  • Chung, J.K.;Kim, W.J.;Park, S.C.;Kang, S.G.;Lim, Y.J.;Kim, C.J.
    • Progress in Superconductivity
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    • v.10 no.2
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    • pp.133-138
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    • 2009
  • The $Nd_{1+x}Ba_{2-x}Cu_3O_{7-{\delta}}$(Nd123) superconductor exhibits high performance in high magnetic field and high temperature. We have studied phase stability for Nd123 under reduced oxygen partial pressure and various heat-treatment conditions. The main phase is Nd123 and some samples contain small amounts of Nd422 depending on the temperature and oxygen partial pressure. The decomposition temperature decreases with decreasing oxygen partial pressure from $1052^{\circ}C(P(O_2)$=150 Torr) to about $845^{\circ}C(P(O_2)$=0.1 Torr). The liquidus line was steeper temperature with decreasing oxygen partial pressure. In same condition of oxygen partial pressure, the region of stable Nd123 phase was formed at slightly higher temperature than the region of stable YBCO phase.

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Characteristics of ITO/polymeric Films with Change of Oxygen Partial Pressure (산소분압의 변화에 따른 ITO/polymeric 박막의 특성)

  • 신성호;김현후
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.8
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    • pp.846-851
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    • 2004
  • Transparent conducting indium tin oxide (TC-ITO) thin films on polymeric substrates have been deposited by a dc reactive magnetron sputtering without heat treatments. The polymeric substrates are acryl (AC), poly carbornate (PC), and polyethlene terephthalate (PET) as well as soda lime glass is also used to compare with the polymeric substrates. Sputtering parameters are an important factor for high quality of TC-ITO thin films prepared on polymeric substrates. Furthermore, the material, electrical and optical properties of as-deposited ITO films are dominated by the ratio of oxygen partial pressure. As the experimental results, the surface roughness of ITO films becomes rough as the oxygen partial pressure increases. The electrical resistivity of as-deposited ITO films decreases initially, and then increases with the increase of oxygen partial pressure. The optical transmittance at visible wavelength for all polymeric substrates is above 82 %.

Dependence of the Structural and Electrical Properties of Co-Sputtered Zn-Doped ITO Thin Films on the Composition and Oxygen Partial Pressure

  • Heo, Gi-Seok;Kim, EunMi
    • Journal of the Korean Ceramic Society
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    • v.50 no.4
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    • pp.288-293
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    • 2013
  • Zn-In-Sn-O films were prepared at room temperature by combinatorial RF-magnetron co-sputtering system. The cationic contents of the films were varied using a compositionally combinatorial technique. The effects of the oxygen partial pressure and film compositionon the structural and electrical properties were investigated. The Zn-In-Sn-O films deposited at Ar gas atmosphere showed an amorphous phaseirrespective of the film composition. However, the amorphous Zn-In-Sn-O films with a Zn content below 30.0 at% were converted into a bixbyite type-ITO polycrystalline phase with an increase in the oxygen partial pressure. The resistivity, carrier concentration, and Hall mobility were strongly affected by the oxygen partial pressure and chemical composition of the film. At sufficiently high carrier densities above $5{\times}10^{18}cm^{-3}$, the conduction behavior of amorphous Zn-In-Sn-O film changes from thermally activated to degenerate band conduction accompanied with high mobility.

Electrical Conductivity and Defect Structure in $SrTiO_3$Thick Film ($SrTiO_3$ 후막의 전기전도도 및 결함구조)

  • 김영호;김호기
    • Journal of the Korean Ceramic Society
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    • v.27 no.7
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    • pp.841-850
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    • 1990
  • The electrical conductivity of SrTiO3 thick films, which has been prepared by screen printing and sintering on polycrystalline Al2O3 substrates, was determined as a function of oxygen partial pressure and temperature. The data showed that electrical conductivity was proportional to the -1/4th power of the oxygen partial pressure for the oxygen partial pressure range from 10-4-10-8 to 10-20 atm and proportional to Po2+1/4 for the oxygen partial pressure range from 10-6-10-4 to 1atm. And then n-p transition region of electrical conductivity moved to lower oxygen partial pressure region as the sintering temperature of thick film specimens increased under about 140$0^{\circ}C$. These data were consistent with the presence of small amounts of acceptor impurities in SrTiO3 thick film which have been diffused from Al2O3 substrate in the range of solid solubility limit.

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Surface Tension of Molten Ag-Sn and Au-Cu Alloys at Different Oxygen Partial Pressures (다양한 산소분압에 따른 용융 Ag-Sn 및 Ag-Cu 합금의 표면장력)

  • Min, Soon-Ki;Lee, Joon-Ho
    • Korean Journal of Materials Research
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    • v.19 no.1
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    • pp.13-17
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    • 2009
  • A semi-empirical method to estimate the surface tension of molten alloys at different oxygen partial pressures is suggested in this study. The surface tension of molten Ag-Sn and Ag-Cu alloys were calculated using the Butler equation with the surface tension value of pure substance at a given oxygen partial pressure. The oxygen partial pressure ranges were $2.86{\times}10^{-12}$$1.24{\times}10^{-9}$ Pa for the Ag-Sn system and $2.27{\times}10^{-11}$$5.68{\times}10^{-4}$ Pa for the Ag-Cu system. In this calculation, the interactions of the adsorbed oxygen with other metallic constituents were ignored. The calculated results of the Ag-Sn alloys were in reasonable accordance with the experimental data within a difference of 8%. For the Ag-Cu alloy system at a higher oxygen partial pressure, the surface tension initially decreased but showed a minimum at $X_{Ag}$ = 0.05 to increase as the silver content increased. This behavior appears to be related to the oxygen adsorption and the corresponding surface segregation of the constituent with a lower surface tension. Nevertheless, the calculated results of the Ag-Cu alloys with the present model were in good agreement with the experimental data within a difference of 10%.

Effect of Oxygen Partial Pressure on the Structural, Optical and Electrical Properties of Sputter-deposited Vanadium Oxide Thin Films (스퍼터링으로 증착된 바나듐 산화막의 구조적, 광학적, 전기적 특성에 미치는 산소 분압의 효과)

  • 최복길;최창규;권광호;김성진;이규대
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.12
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    • pp.1008-1015
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    • 2001
  • Thin films of vanadium oxide(VO$\_$x/) have been deposited by r.f. magnetron sputtering from V$_2$O$\_$5/ target in gas mixture of argon and oxygen. The oxygen/(oxygen+argon) partial pressure ratio is changed from 0% to 8%. Crystal structure, chemical composition, bonding, optical and electrical properties of films sputter-deposited under different oxygen gas pressures are characterized through XPS, AES, RBS, FTIR, optical absorption and electrical conductivity measurements. V$_2$O$\_$5/ and lower oxides co-exist in sputter-deposited films and as the oxygen partial pressure is increased the films become more stoichiometric V$_2$O$\_$5/. The increase of O/V ratio with increasing oxygen gas pressure is attributed to the partial filling of oxygen vacancies through diffusion. It is observed that the oxygen atoms located on the V-O plane of V$_2$O$\_$5/ layer participate more readily in the oxidation process. With increasing oxygen gas pressure indirect and direct optical band gaps are increased, but thermal activation energies are decreased.

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Effect of Partial Oxygen Pressure on the Growth and Defense Enzyme Activities of Streptomyces coelicolor in continuous culture system (Streptomyces coelicolor의 연속 배양시 산소 분압에 따른 방어 효소의 활성 변화)

  • 박용두;이계준;노정혜
    • Microbiology and Biotechnology Letters
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    • v.22 no.5
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    • pp.538-543
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    • 1994
  • Effect of partial oxygen pressure on the cell growth and the activities of oxidative defense enzymes were measured in the continuous culture of Streptomyces coelicolor. Both the wild type and the mutant strain resistant to hydrogen peroxide were cultured and the dry cell weight of the two cultures were measured at different oxygen tensions. Growth of the wild type was inhibited by oxygen at above 0.5 vvm. Growth of the hydrogen peroxide resistant mutant was stimulated by pure oxygen at 0.5 vvm but was inhibited by oxygen at 1.0 vvm. Therefore, growth of the hydrogen peroxide resistant mutant was less affected by the deleterious oxidative stress of oxygen. Activities of the several defense enzymes were also measured at different oxygen tensions. Activities of catalase and glucose-6-phosphate dehydrogenase increased significantly as oxygen pressure increased in the wild type culture. In the mutant, however, increase in those enzyme activities was not obvious whereas the uninduced levels of the above enzymes were higher than those of wild type. As judged by Western blotting, the amount of the major catalase increased as the oxygen pressure increased. This indicates that the induction of the catalase activity by oxygen pressure is mostly due to the increase in the expression level for the major catalase.

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Effects of Oxygen Partial Pressure on the Structural Properties of Sputtered Vanadium Oxide Thin Films (스퍼터된 바나듐 산화막의 구조적 특성에 미치는 산소 분압의 효과)

  • 최복길;최용남;최창규;권광호
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.435-438
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    • 2001
  • Thin films of vanadium oxide(VO$\sub$x/) have been deposited by r.f. magnetron sputtering from V$_2$O$\sub$5/ target in gas mixture of argon and oxygen. The oxygen/(oxygen+argon) partial pressure ratio is changed from 0% to 8%. Crystal structure, chemical composition and bonding properties of films sputter-deposited under different oxygen gas pressures are characterized through XRO, XPS, RBS and FTIR measurements. All the films prepared below 8% O$_2$ are amorphous, and those prepared without oxygen are gray indicating the presence of V$_2$O$\sub$$_4$/ phase in the films. V$_2$O$\sub$5/ and lower oxides co-exist in sputter-deposited films and as the oxygen partial pressure is increased the films become more stoichiometric V$_2$O$\sub$5/. The increase of O/V ratio with increasing oxygen gas pressure is attributed to the partial filling of oxygen vacancies through diffusion. It is observed that the oxygen atoms. located on the V-O plane of V$_2$O$\sub$5/ layer participate more readily in the oxidation process.

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Characteristics of ITO Thin Films on Polymeric Substrates with Oxygen Partial Pressure Ratio (산소분압비에 따른 고분자 기판 상에 ITO박막의 특성)

  • Kim, H.H.;Lee, Mu-Yeong;Kim, K.T.;Yoon, S.H;Park, D.H.;Park, C.H.;Lim, K.J.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.849-852
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    • 2004
  • Indium tin oxide (ITO) thin films on polymeric substrates such as acryl (AC), Poly carbornate (PC), polypropylene (PP), and polyethlene terephthalate (PET) have been deposited by a do reactive magnetron sputtering without heat treatments. Sputtering parameters is an important factor for high Qualify of ITO thin films prepared on polymeric substrates. Furthermore, the material, electrical and optical properties of as-deposited ITO films are dominated by the ratio of oxygen partial pressure. As the experimental results the surface roughness of ITO films becomes rough as the oxygen partial pressure Increases. The electrical resistivity of as-deposited ITO films decreases initially, and then increases with the increase of oxygen partial pressure. The optical transmittance at visible wavelength for all polymeric substrates is above 80%.

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