• 제목/요약/키워드: n-doped

검색결과 1,041건 처리시간 0.021초

Effect on N Defect in Cu-doped III-nitride Semiconductors

  • Kang, Byung-Sub;Lee, Jae-Kwang;Lim, Yong-Sik;Song, Kie-Moon;Chae, Kwang-Pyo
    • Journal of Magnetics
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    • 제16권4호
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    • pp.332-336
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    • 2011
  • We studied the effect on the electronic and magnetic properties of the N defect in clean and Cu-doped wurtzite III-nitrides by using the first-principles calculations. When it is doped two Cu atoms in the nearest neighboring sites, the system of AlN, GaN, or InN with the N vacancy is energetically more favorable than that without the N vacancy site. When the Cu concentration increases, the total magnetic moment of a supercell becomes small. The ferromagnetism of Cu atom is very low due to the weak 3d-3d coupling. It is noticeable that the spin-exchange interaction between the Cu-3d and N defect states is important.

고농도의 Mg가 도핑된 GaN층을 이용한 GaN계 청자색 레이저다이오드의 동작 전압 감소 (Reduction of Operating Voltage of GaN-based Blue-violet Laser Diode by using Highly Mg Doped GaN Layer)

  • 곽준섭
    • 한국전기전자재료학회논문지
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    • 제17권7호
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    • pp.764-769
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    • 2004
  • In order to reduce operating voltage of the GaN based blue-violet laser diodes, the effect of highly Mg doped GaN layer, which was grown below ohmic contact metals, on contact resistivity as well as operating voltage has been investigated. The addition of the highly Mg doped GaN layer greatly reduced contact resistivity of Pd/Pt/Au ohmic contacts from $5.2 \times {10}^-2 \Omegaㆍ$\textrm{cm}^2$ to 7.5 \times {10}^-4 \Omegaㆍ$\textrm{cm}^2$$. In addition, it also decreased device voltage at 20 mA by more than 3 V. Temperature- dependent sheet resistivity of the highly Mg doped GaN layer suggested that the reduction of the contact resistivity could be attributed to predominant current flow at the interface between the Pd/Pt/Au contacts and p-GaN through a deep level defect band, rather than the valence band.

Theoretical study of H2 evolution on N-doped monolayer graphene

  • 김계엽;한승우
    • EDISON SW 활용 경진대회 논문집
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    • 제3회(2014년)
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    • pp.485-487
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    • 2014
  • Nitrogen이 도핑된 graphene에서의 hydrogen evolution에 대한 촉매효과에 대해서 연구를 진행하였다. Reaction free energy를 계산하기 위해서 많은 N-doped graphene 모델을 계산하였으며 pH 조건, silicon cathode의 영향 그리고 zero point energy의 효과를 고려하였다. Volcano plot에 의하면 "pyrol" like model과 N-doped armchair graphene model (aGNR-N1)이 좋은 촉매효과를 가짐을 밝혔다. 또한 free energy diagram을 통하여 "pyrol"과 "aGNR-N1"이 좋은 active site가 될 수 있음을 확인하였고 pH가 증가함에 따라 $H^+$의 에너지가 증가함에 따라 촉매 효과가 줄어듬을 확인하였다.

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p-n Heterojunction Composed of n-ZnO/p-Zn-doped InP

  • Shim, Eun-Sub;Kang, Hong-Seong;Kang, Jeong-Seok;Pang, Seong-Sik;Lee, Sang-Yeol
    • Transactions on Electrical and Electronic Materials
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    • 제3권1호
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    • pp.1-3
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    • 2002
  • A p-n junction was obtained by the deposition of an n-type ZnO thin film on a p-type Zn-doped InP substrate. The Zn-doped InP substrate has been made by the diffusion of Zn with sealed ampoule technique. The ZnO deposition process was performed by pulsed laser deposition (PLD). The p-n junction was formed and showed typical I-V characteristics. We will also discuss about the realization of an ultraviolet light-emitting diode (LED). The structure of n-ZnO/p-Zn-doped InP could be a good candidate for the realization of an ultraviolet light-emitting diode or an ultraviolet laser diode.

AC Conductivity of $(Sr_{0.75}$,$La_{0.25}$) $TiO_3/SrTiO_3$ Superlattices

  • 최의영;최재두;이재찬
    • 한국재료학회:학술대회논문집
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    • 한국재료학회 2011년도 춘계학술발표대회
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    • pp.31.2-31.2
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    • 2011
  • We have investigated frequency dependant conductivity (or permittivity) of low dimensional oxide structures represented by [($Sr_{0.75}$, $La_{0.25}$)$TiO_3$]$_1$/1$[SrTiO_3]_n$ superlattices. The low dimensional oxide superlattice was made by cumulative stacking of one unit cell thick La doped $SrTiO_3$ and $SrTiO_3$ with variable thickness from 1 to 6 unit cell, i,e, [($Sr_{0.75}$, $La_{0.25}$)$TiO_3$]$_1$/$[SrTiO_3]_n$ (n=1, 2, 3, 4, 5, 6). We found two kinds of relaxation when n is 3 and 4, while, inductance component was observed at n=1. This behavior can be explained by electron modulation in ($Sr_{0.75}$, $La_{0.25}$)$TiO_3/SrTiO_3$ superlattices. When n is 1, electrons by La doping well extend to un-doped layer. Therefore, the transport of superlattices follows bulk-like behavior. On the other hand, as n increased, the doped electrons became two types of carrier: one localized and the other extended. These results in two kinds of transport phase. At further increase of n, most of doped electrons are localized at the doped layer. This result shows that dimensionality of the oxide structure significantly affect the transport of oxide nanostructures.

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Visible-photoresponsive Nitrogen-Doped Mesoporous TiO2 Films for Photoelectrochemical Cells

  • Bae, Jae-Young;Yun, Tae-Kwan;Ahn, Kwang-Soon;Kim, Jae-Hong
    • Bulletin of the Korean Chemical Society
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    • 제31권4호
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    • pp.925-928
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    • 2010
  • Nitrogen-doped $TiO_2$ ($TiO_2$:N) nano-particles with a pure anatase crystalline structure were successfully synthesized through the hydrolysis of $TiCl_4$ in an ammonia aqueous solution. The samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), $N_2$-sorption, and UV-vis diffuse reflectance spectra (UV-vis DRS) techniques. The absorption edge of nitrogen-doped $TiO_2$ shifted into the visible wavelength region. The photoelectrochemical (PEC) performances were investigated for the $TiO_2$ mesoporous electrodes doped with different nitrogen concentrations. The $TiO_2$:N electrodes exhibited much higher PEC responses compared to the pure $TiO_2$ electrode because of the significantly enhanced visible-photoresponsibility of the $TiO_2$:N electrodes.

Mg도핑된 GaN 반도체 박막의 전자스핀공명 (Electron Spin Resonance from Mg-doped GaN Semiconductor Thin Films)

  • 박효열
    • 반도체디스플레이기술학회지
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    • 제4권2호
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    • pp.1-5
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    • 2005
  • Electon spin resonance measurements have been performed on the Mg-doped wurtzite GaN thin films grown on sapphire substrates by low-pressure metal-organic chemical vapor deposition. The sample set included films as-grown with the regular Mg doped and Mg delta doped samples and the corresponding annealed ones. The resonance signal has been observed from the annealed Mg delta-doped sample with the Lande g value of 2.029. This indicates that the singlet resonance signal originates from the neutral Mg acceptor located at 0.24 eV above the valence band edge and 0.13 eV above the Fermi level because of the nuclear hyperfine spin 1=0 of Mg and the larger value than the free electron g=2.0023.

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Fluorine 첨가에 의한 F-doped SiOC : H 박막의 저 굴절률 특성 (Refractive index control of F-doped SiOC : H thin films by addition fluorine)

  • 윤석규;강삼묵;정원석;박우정;윤대호
    • 한국결정성장학회지
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    • 제17권2호
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    • pp.47-51
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    • 2007
  • 저굴절 재료인 F-doped SiOC : H 박막을 Si 웨이퍼와 유리기판위에 rf power, 기판온도, 그리고 가스유량($SiH_4,\;CF_4$ and $N_2O$)을 변수로 하여 PECVD법으로 증착하였다. 기판 온도와 rf power증가에 따라 F-doped SiOC : H 박막의 굴절률은 감소하는 경향을 보였다. $N_2O$ 가스 유량이 감소함에 따라 증착된 박막의 굴절률은 감소하였으며, rf power가 180W 기판온도 $100^{\circ}C$, 그리고 $N_2O$ 가스를 첨가하지 않은 조건에서 증착한 박막은 최소 굴절률인 1.3778을 갖는 것을 알 수 있었다. Rf power 60W에서 180W로 증가시킴에 따라 증착된 박막의 불소 함량은 1.9at%에서 2.4at%로 증가하였으며 이러한 이유로 박막의 굴절률은 감소하는 경향을 나타냈다.

질소를 도핑한 TiO2를 이용한 부식산 분해 (Degradation of Humic Acid Using N-Doped TiO2)

  • 소지양;이동석
    • 산업기술연구
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    • 제31권B호
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    • pp.119-125
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    • 2011
  • N-doped Titanium oxides were prepared by using urea as a source of nitrogen. The photoactivities of the doped $TiO_2$ were evaluated on the basis of degradation of humic acid in aqueous solutions with different light sources, ultraviolet lamp, fluorescent lamp and solar light. XRD analysis was conducted to identify the crystal structure of the synthesized photocatalysts. N-doped $TiO_2$ and $pure-TiO_2$ was anatase type. SEM results showed that spherical particles were formed, which are the characteristics of the anatase form. N doped $TiO_2$ showed higher $UV_{254}$ decrease ratio and DOC removal ratio compared to $pure-TiO_2$. The humic acid degradation reaction using the UV-A lamp and UV-C lamp was assigned to pseudo-first order reaction. For solar light, only $pure-TiO_2$ and $N-TiO_2$ exhibited the pseudo-first order reaction.

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HVPE에 의한 불순물이 첨가된 GaN 박막의 제작 (The preparation of the doped GaN thin films by HVPE)

  • 정성훈;송복식;문동찬;김선태
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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    • pp.66-69
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    • 1997
  • The p-GaN fins doped with the impurity of Zn were grown on n-GaN films to prevent the defects from the lattice mismatch with sapphire substrates by HVPE. For growth of the high quality n-GaN, the optimized conditions were at first deduced from the results of various HCI gas flow rates and growth temperatures. On the basis of these conditions, p-GaN films were grown and investigated of the characteristics. The FWHM of the double crystal rocking curve of n-GaN was decreased and the hexagonal phases on the surface of GaN films were tend to be vivid with the inoement of HCI gas flow rates. Finally the n-type GaN films with FWHM of 648arcsec were obtained at 10cc/min of HCI gas. As the GaN films were grown with the above conditions, Zn was introduced in the form of vapor as a dopant for p-GaN films. But when Zn vaporized at 77$0^{\circ}C$ was doped to the films, the crystallites of Zn were distributed uniformly on the surface of the GaN film due to the over-doped.

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