• Title/Summary/Keyword: In-doped

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Ga-doped ZnO nanorod arrays grown by thermal evaporation and their electrical behavior (수직 배향된 Ga-doped ZnO nanorods의 합성과 전기적 특성)

  • Ahn, C.H.;Han, W.S.;Kong, B.H.;Kim, Y.Y.;Cho, H.K.;Kim, J.J.;Kim, H.S.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.11a
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    • pp.414-414
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    • 2008
  • Vertically well-aligned Ga-doped ZnO nanorods with different Ga contents were grown by thermal evaporation on a ZnO template. The Ga-doped ZnO nanorods synthesized with 50 wt % Ga with respect to the Zn content showed maximum compressive stress relative to the ZnO template, which led to a rapid growth rate along the c-axis due to the rapid release of stored strain energy. A further increase in the Ga content improved the conductivity of the nanorods due to the substitutional incorporation of Ga atoms in the Zn sites based on a decrease in lattice spacing. The p-n diode structure with Ga-doped ZnO nanorods, as a n-type, displayed a distinct white light luminescence from the side-view of the device, showing weak ultraviolet and various deep-level emissions.

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Electrical, Electronic Structure and Optical Properties of Undoped and Na-doped NiO Thin Films

  • Denny, Yus Rama;Lee, Kangil;Seo, Soonjoo;Oh, Suhk Kun;Kang, Hee Jae;Yang, Dong-Seok
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.193.1-193.1
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    • 2014
  • This study was to investigate the electronic structure and optical properties of Na doped into NiO thin film using XPS and REELS. The films were grown by electron beam evaporation with varying the annealing temperature. The relationship between the electrical characteristics with the local structure of NiO thin films was also discussed. The x-ray photoelectron results showed that the Ni 2p spectra for all films consist of Ni 2p3/2 which indicate the presence of Ni-O bond from NiO phase and for the annealed film at temperature above $200^{\circ}C$ shows the coexist Ni oxide and Ni metal phase. The reflection electron energy loss spectroscopy spectra showed that the band gaps of the NiO thin films were slightly decreased with Na-doped into films. The Na-doped NiO showed relatively low resistivity compared to the undoped NiO thin films. In addition, the Na-doped NiO thin films deposited at room temperature showed the best properties, such as a p-type semiconducting with low electrical resistivity of $11.57{\Omega}.cm$ and high optical transmittance of ~80% in the visible light region. These results indicate that the Na doping followed by annealing process plays a crucial in enhancing the electrical and optical properties of NiO thin films. We believe that our results can be a good guide for those growing NiO thin films with the purpose of device applications, which require deposited at room temperature.

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Synthesis of Amorphous Er3+-Yb3+ Co-doped TiO2 and Its Application as a Scattering Layer for Dye-sensitized Solar Cells

  • Han, Chi-Hwan;Lee, Hak-Soo;Lee, Kyung-Won;Han, Sang-Do;Singh, Ishwar
    • Bulletin of the Korean Chemical Society
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    • v.30 no.1
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    • pp.219-223
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    • 2009
  • $TiO_2$ doped with $Er^{3+\;and\;Yb^{3+}$ was used for fabricating a scattering layer and a nano-crystalline $TiO_2$ electrode layer to be used in dye-sensitized solar cells. The material was prepared using a new sol-gel combustion hybrid method with acetylene black as fuel. The $Er^{3+}$-$Yb^{3+}$ co-doped titanium oxide powder synthesized at 700oC had embossed structure morphology with a size between 27 to 54 nm that agglomerated to produce micron size particles, as observed by the scanning electron micrographs. The XRD patterns showed that the $Er^{3+}$-$Yb^{3+}$ co-doped titanium oxide had an amorphous structure, while using the same method without doping $Er^{3+}\;or\;Yb^{3+},\;TiO_2$ was obtained in the crystallite form with thea dominance of rutile phase. Fabricating a bilayer structure consisting of nano-crystalline $TiO_2$ and the synthesized $Er^{3+}$-$Yb^{3+}$ co-doped titanium oxide showed better scattering property, with an overall increase of 15.6% in efficiency of the solar cell with respect to a single nano-crystalline $TiO_2$ layer.

Electrical, Structural and Optical Characteristic Analysis of Al-doped ZnO Film Deposited by Atomic Layer Deposition (Atomic Layer Deposition으로 증착된 Al-doped ZnO Film의 전기적, 구조적 및 광학적 특성 분석)

  • Lim, Jung-Soo;Jeong, Kwang-Seok;Shin, Hong-Sik;Yun, Ho-Jin;Yang, Seung-Dong;Kim, Yu-Mi;Lee, Hi-Deok;Lee, Ga-Won
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.24 no.6
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    • pp.491-496
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    • 2011
  • Al-doped ZnO film on glass substrate is deposited by ALD in low temperature, using 4-step process (DEZ-$H_2O$-TMA-$H_2O$). To find out the optimal film condition for TCO material, we fabricate Al-doped ZnO films by increasing Al doping concentration at $100^{\circ}C$, so that the Al-doped film of 5 at% shows the lowest resistivity ($1.057{\times}10^{-2}{\Omega}{\cdot}cm$) and the largest grain size (38.047 nm). Afterwards, the electrical and physical characteristics in Al-doped films of 5 at% are also compared in accordance with increasing deposition temperature. All the films show the optical transmittance over 80% and the film deposited at $250^{\circ}C$ demonstrates the superior resistivity ($1.237{\times}10^{-4}{\Omega}{\cdot}cm$).

RECYCLING PROCESS OF U3O8 POWDER IN MnO-Al2O3 DOPED LARGE GRAIN UO2 PELLETS

  • Oh, Jang Soo;Kim, Dong-Joo;Yang, Jae Ho;Kim, Keon Sik;Rhee, Young Woo;Koo, Yang-Hyun
    • Nuclear Engineering and Technology
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    • v.46 no.1
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    • pp.117-124
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    • 2014
  • The effect of various process variables on the powder properties of recycled $U_3O_8$ from MnO-$Al_2O_3$ doped large grain $UO_2$ pellets and the effect of those recycled $U_3O_8$ powders on the sintered density and grain size of MnO-$Al_2O_3$ doped large grain $UO_2$ pellets have been investigated. The evolution of morphology, size, and BET surface area of the recycled $U_3O_8$ powders according to the respective variation of the thermo-mechanical treatment variables of oxidation temperature, powder milling, and sequential cyclic heat treatment of oxidation and then reduction was examined. The correlation between the BET surface area of recycled $U_3O_8$ powder and the sintered pellet properties of MnO-$Al_2O_3$ doped pellets showed that the pellet density and grain size of doped pellets were increased and then saturated by increasing the BET surface area of the recycled $U_3O_8$ powder. The density and grain size of the pellets were maximized when the BET surface area of the recycled $U_3O_8$ powder was in the vicinity of $3m^2/g$. Among the process variables applied in this study, the cyclic heat treatment followed by low temperature oxidation was a potential process combination to obtain the sinter-active $U_3O_8$ powder.

The Thermoelectric Properties of p-type SiGe Alloys Prepared by RF Induction Furnace (고주파 진공유도로로 제작한 p형 SiGe 합금의 열전변환물성)

  • 이용주;배철훈
    • Journal of the Korean Ceramic Society
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    • v.37 no.5
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    • pp.432-437
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    • 2000
  • Thermoelectric properties of p-type SiGe alloys prepared by a RF inductive furnace were investigated. Non-doped Si80Ge20 alloys were fabricated by control of the quantity of volatile Ge. The carrier of p-type SiGe alloy was controlled by B-doping. B doped p-type SiGe alloys were synthesized by melting the mixture of Ge and Si containing B. The effects of sintering/annealing conditions and compaction pressure on thermoelectric properties (electrical conductivity and Seebeck coefficient) were investigated. For nondoped SiGe alloys, electrical conductivity increased with increasing temperatures and Seebeck coefficient was measured negative showing a typical n-type semiconductivity. On the other hand, B-doped SiGe alloys exhibited positive Seebeck coefficient and their electrical conductivity decreased with increasing temperatures. Thermoelectric properties were more sensitive to compaction pressure than annealing time. The highest power factor obtained in this work was 8.89${\times}$10-6J/cm$.$K2$.$s for 1 at% B-doped SiGe alloy.

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Sintering Behaviors of ITO Ceramics with Additions of TiO$_2$ (TiO$_2$첨가에 따른 ITO 세라믹스의 소결 거동)

  • 정성경;김봉철;장세홍;김정주
    • Journal of the Korean Ceramic Society
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    • v.35 no.4
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    • pp.347-354
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    • 1998
  • Densification and grain growth behaviors of ITO ceramics were investigated as a function of TiO2 ad-ditions. TiO2 addition led to inhibition of the grain growth and promotion of the densification of ITO ceram-ics. From the microstructure observation it was found that the crack-like voids which were formed in pure ITO specimens decreased with increase of TiO2 additon. The grain growth exponent(n) was measur-ed to be 4 for pure ITO 3 for TiO2-doped ITO specimens respectively. It was supposed that the grain boun-dary migration of pure ITO ceramics was controlled by the pores which were moved by surface diffusion. On the contrary the grain boundary migration of TiO2-doped ITO specimens was depressed by solute drag effect. The activation energies for grain growth were measured to be 1013 kJ/mol for pure ITO ceramics and 460kJ/mol for TiO2-doped ITO specimens respectively.

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Facile Modulation of Electrical Properties on Al doped ZnO by Hydrogen Peroxide Immersion Process at Room Temperature

  • Park, Hyun-Woo;Chung, Kwun-Bum
    • Applied Science and Convergence Technology
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    • v.26 no.3
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    • pp.43-46
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    • 2017
  • Aluminum-doped ZnO (AZO) thin films were deposited by atomic layer deposition (ALD) with respect to the Al doping concentrations. In order to explain the chemical stability and electrical properties of the AZO thin films after hydrogen peroxide ($H_2O_2$) solution immersion treatment at room temperature, we investigated correlations between the electrical resistivity and the electronic structure, such as chemical bonding state, conduction band, band edge state below conduction band, and band alignment. Al-doped at ~ 10 at % showed not only a dramatic improvement of the electrical resistivity but also excellent chemical stability, both of which are strongly associated with changes of chemical bonding states and band edge states below the conduction band.

The Hydrogen Gas Sensing Characteristics of the Pd-doped $SnO_2$ Thin Films Prepared by Sputtering (스퍼터링법으로 제조된 Pd-doped $SnO_2$ 박막의 수소가스 감도 특성)

  • 차경현;김영우;박희찬;김광호
    • Journal of the Korean Ceramic Society
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    • v.30 no.9
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    • pp.701-708
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    • 1993
  • Pd-doped SnO2 thin films for hydrogen gas sensing were fabricated by reactive fo magnetron sputtering and were studied on effects of film thickness and Pd doping content. Pd doping caused the optimum sensor operation temperature to reduce down to ~25$0^{\circ}C$ and also enhanced gas sensitivity, compared with undoped SnO2 film. Gas sensitivity depended on the film thickness. The sensitivity increased with decreasing the film thickness, showing maximum sensitivities at the thickness of 730$\AA$ and 300~400$\AA$ for the undoped SnO2 and the Pd-doped SnO2 film, respectively. Further decrease of the film thickness beyond these thickness ranges, however, resulted in the reduction of sensitivity again.

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Design and Control of Gain-Flattened Erbium-Doped Fiber Amplifier for WDM Applications

  • Kim, Hyang-Kyun;Park, Seo-Yeon;Lee, Dong-Ho;Park, Chang-Soo
    • ETRI Journal
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    • v.20 no.1
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    • pp.28-36
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    • 1998
  • A simple experimental method to design gain-flattened erbium-doped fiber amplifier is proposed and demonstrated based on the two linear relations between the output power and the pump power, and between the gain and the length of the eribium-doped fiber at the gain flattened state. The spectral gain variation of the eribium-doped fiber amplifiber constructed by this method was less than 0.4 dB over 12 nm (1,545~1,557nm) wavelength region. The gain flatness is also controlled within 0.4 dB over the input power range of -30~-15dBm/ch through the feedback control utilizing the amplified spontaneous emission power in the 1,530 nm region.

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