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  • 제목/요약/키워드: Ga doped

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Effect of Ga Dopants on Electrical and Optical Characteristics of ZnO Thin Films (Ga 첨가물이 ZnO의 전기적, 광학적 특성에 미치는 영향)

  • Kim, Jun-Sik;Jang, Gun-Eik
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.9
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    • pp.685-690
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    • 2010
  • ZnO with the wide band gap near 3.37 eV is typically an n-type semiconductor in which deviation from stoichiometry is electrically active. It was known that the films with a resistivity of the order of 104Ωcm is not easy to obtain. In order to improve electrical characteristic of ZnO, we added 1, 3, 5 wt% Ga element in ZnO. The Ga-doped ZnO (GZO) was grown on a glass substrate by radio frequency (RF) magnetron sputtering at the temperature range from 100 to 500C. X-ray diffraction (XRD) patterns of GZO films showed preferable crystal orientation of (002) plane. The lowest resistivity of the GZO films was 8.9×104Ωcm. GZO films significantly influenced by the working temperature. The average transmittance of the films was over 80% in the visible ranges.

Analysis of Transport Parameters in an Interacting Two-Band Model with Application to p+-GaAs

  • Kim, B.W.;Majerfeld, A.
    • ETRI Journal
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    • v.17 no.3
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    • pp.17-43
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    • 1995
  • We present a comprehensive derivation of the transport of holes involving an interacting two-valence-band system in terms of a generalized relaxation time approach. We sole a pair of semiclassical Boltzmann equations in a general way first, and then employ the conventional relaxation time concept to simplify the results. For polar optical phonon scattering, we develop a simple method th compensate for the inherent deficiencies in the relaxation time concept and apply it to calculate effective relaxation times separately for each band. Also, formulas for scattering rates and momentum relaxation times for the two-band model are presented for all the major scattering mechanisms for p-type GaAs for simple, practical mobility calculations. Finally, in the newly proposed theoretical frame-work, first-principles calculations for the Hall mobility and Hall factor of p-type GaAs at room temperature are carried out with no adjustable parameters in order to obtain a direct comparison between the theory and recent available experimental results, which would stimulate further analysis toward better understanding of the complex transport properties of the valence band. The calculated Hall mobilities show a general agreement with our experimental data for carbon doped p-GaAs samples in a range of degenerate hole densities. The calculated Hall factors show rH=1.25~1.75 over all hole densities(2×10171×1020cm3 considered in the calculations.

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The Crystal Growth and Electrical Characteristics of AlxGa1xSb (AlxGa1xSb 결정 성장과 전기적 특성)

  • 이재구;정성훈;송복식;문동찬;김선태
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1996.05a
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    • pp.185-188
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    • 1996
  • The doped n-type AlxGa1xSb crystals were grown by the vertical Bridgman method at composition ratio x=0, x=0.1, x=02 respectively. The lattice constants of the AlxGa1xSb crystals were 6.096\AA, 6.097\AA, 6.106\AA at composition ratio respectively. The carrier concentration, the resistivity, and the carrier mobility measured by the Van der Pauw method at x-0 were n≡1 x 1017cm3, ρ≡0.15 Ω-cm, μn≡500 cm2V1sec1 at 300K. The carrier concentration, the resistivity, and the carrier mobility measured by the Van der Pauw method at x=0.1 were n≡2.96 x 1015cm3, ρ≡103 cm2V1sec1 at 300K.

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GaN기반 LED 응용을 AZO, Ni/AZO 및 NiOx/AZO의 전기적.광학적 특성

  • Ju, Dong-Hyeok;Lee, Hui-Gwan;Yu, Jae-Su
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.08a
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    • pp.249-249
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    • 2011
  • 투명전도성산화물(transparent conducting oxides, TCOs) 박막은 전기 전도성과 광투과성이 우수하여 유기발광다이오드(organic light-emitting diode, OLED), 태양전지(solar cell), 발광다이오드(LED) 등의 광전자 소자에 널리 응용되고 있다. 특히 LED에서 p-GaN층에서 전류가 층안에서 충분하게 확산되지 않기 때문에, TCO는 균일하게 전류를 흘려보내기 위해서 전류확산층(current spreading layer)으로 사용된다. 그 중 널리 쓰이는 산화인듐주석(indium tin oxide, ITO)은 고가의 indium가격과 인체에 유해한 독성 등이 문제점으로 지적되고 있다. 따라서 indium의 함량을 저감하거나 함유하지 않은 새로운 조성의 친환경적 대체 TCO 개발에 대한 연구가 많이 진행되고 있다. 이러한 반도체 재료 중 하나인 AZO (Al-doped zinc oxide, Al2O3 : 2wt.%)는 3.3 eV의 넓은 에너지 밴드갭을 가지며, 가시광선 및 근적외선 파장영역에서 높은 투과율을 나타낸다. 따라서 본 연구에서는 GaN기반 LED 응용을 위한 전류확산층으로 ITO 대신 AZO의 특성을 연구하였다. 박막 증착율이 높고, 제작과정의 조정이 용이한 RF magnetron 스퍼터를 이용하여 glass기판 위에 AZO, Ni/AZO, NiOx/AZO를 증착하였다. 이어서 N2 분위기에서 다양한 온도 조건에서 열처리(rapid thermal annealing, RTA)하여 전기적 광학적 특성에 대하여 비교 분석하였다.

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Observation of Unusual Structural Phase Transition in VO2 Thin Film on GaN Substrate

  • Yang, Hyeong-U;Son, Jeong-In;Cha, Seung-Nam;Kim, Jong-Min;Gang, Dae-Jun
    • Proceedings of the Korean Vacuum Society Conference
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    • 2012.02a
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    • pp.573-573
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    • 2012
  • High quality VO2 thin films were successfully grown on GaN substrate by optimizing oxygen partial pressure during the growth using RF sputtering technique. The VO2 thin film grown on GaN substrate exhibited an unusual metal insulator transition behavior, which was known to be observed only either in doped sample or under uniaxial stress. Raman spectra also confirmed that metal insulator transition occurred from monoclinic M1 to rutile R phase via monoclinic M2 phase with increasing temperature. We believe that large lattice mismatch between VO2 and GaN substrate may cause M2 phase to be thermodynamically stable. Optical transmittance and its electrical switching behavior were carefully investigated to elucidate the underlying physics of its metal insulator transition behavior. This study may lead to a unique opportunity to better understand the growth mechanism of M2 phase dominant VO2 thin films.

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Fabrication of Fe-doped LaGaO3 Perovskite Mixed Conductor and Improvement of Oxygen Permeability by Screen Printing Coating (Fe가 Doping 된 LaGaO3 폐롭스카이트 혼합 전도체의 제조 및 코팅에 따른 산소투과 성능 향상)

  • Lim, Kyung Tae;Cho, Tong Lae;Lee, Kee Sung;Woo, Sang Kuk;Park, Kee Bae;Kim, Jong Won
    • Journal of Hydrogen and New Energy
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    • v.12 no.2
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    • pp.137-146
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    • 2001
  • 고상 반응법을 이용하여 La0.7Sr0.3Ga0.6Fe0.4O3δ 분말을 합성하고 혼합전도체 분리막을 소결하여 제조하였다. 제조된 분리막은 LaGaO3에 일치하는 폐롭스카이트 결정구조를 나타내었으며 95% 이상의 높은 상대밀도를 나타내었다. 스크린 프린팅 방법으로 La0.6Sr0.4CoO3δ 후막을 disk의 양 표면에 코팅하였으며 코팅 막은 비교적 치밀한 미세구조를 나타내었다. 코팅되지 않은 분리막과 코팅된 분리막의 산소투과 성능을 비교 실험한 결과 850C에서 동일한 두께의 코팅된 분리막의 정상상태 산소 투과 유속이 0.7m/min.cm2 정도로 코팅되지 않은 분리막에 비해 약 2~3배로 높게 나타났다.

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A Study on the Breakdown in MHEMTs with InAlAs/InGaAs Heterostructure Grown on the GaAs substrate (InAlAs/InGaAs/GaAs MHEMT 소자의 항복 특성에 관한 연구)

  • Son, Myung-Sik
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.48 no.11
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    • pp.1-8
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    • 2011
  • One of the most important parameters that limit maximum output power of transistor is breakdown. InAlAs/InGaAs/GaAs Metamorphic HEMTs (MHEMTs) have some advantages, especially for cost, compared with InP-based ones. However, GaAs-based MHEMTs and InP-based HEMTs are limited by lower breakdown voltage for output power even though they have good microwave and millimeter-wave frequency performance with lower minimum noise figure. In this paper, InAlAs/InxGa1xAs/GaAs MHEMTs are simulated and analyzed for breakdown. The parameters affecting breakdown are investigated in the fabricated 0.1-μm Γ-gate MHEMT device having the modulation-doped In0.52Al0.48As/In0.53Ga0.47As heterostructure on the GaAs wafer using the hydrodynamic transport model of a 2D commercial device simulator. The impact ionization and gate field effect in the fabricated device including deep-level traps are analyzed for breakdown. In addition, Indium mole-fraction-dependent impact ionization rates are proposed empirically for In0.52Al0.48As/InxGa1xAs/GaAs MHEMTs.

Growth and characterization of GaAs and AlGaAs with MBE growth temperature (MBE 성장온도에 따른 GaAs 및 AlGaAs의 전기광학적 특성)

  • Seung Woong Lee;Hoon Young Cho;Eun Kyu Kim;Suk-Ki Min;Jung Ho Park
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.4 no.1
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    • pp.11-20
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    • 1994
  • GaAs and AlGaAs epi-layers were grown on semi-insulating (100) GaAs substrate by molecular beam epitaxy (MBE) and their electrical and optical properties have been investigated by several measurements. In undoped GaAs, the p-type GaAs layers with the good surface morphology were obtained under the growth conditions of the substrate temperatures ranging from 570 to 585C and the As4/Ga ratios from 17 to 22. In the samples with the growth rates of the ranges of 0.9 1.1μm/h, the impurity concentrations were in the ranges of 1.5×1014 5.6×1014cm3 with the Hall mobilities of 590 410cm2/Vs. In the Si-doped GaAs, the n-type GaAs layers with low electro trap, only two hole deep levels were observed with uniform doping profiles (<1%). AlGaAs layers with good surface morphology and crystallinity were grown under an optimum condition of the substrate temperature, 600C. 8 deep level defects were observed between 0.17~0.85eV in undoped AlGaAs layers.

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Physical Characterization of GaAs/AlxGa1xAs/GaAs Heterostructures by Deep Level transient Spectroscopy (DLTS 방법에 의한 GaAs/AlxGa1xAs/GaAs 이종구조의 물성분석에 관한 연구)

  • Lee, Won-Seop;Choe, Gwang-Su
    • Korean Journal of Materials Research
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    • v.9 no.5
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    • pp.460-466
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    • 1999
  • The deep level electron traps in AP-MOCVD GaAs/undoped Al\ulcornerGa\ulcornerAs/n-type GaAs heterostructures have been investigated by means of Deep Level Transient Spectroscopy DLTS). In terms of the experimental procedure, GaAs/undoped Al\ulcornerGa\ulcornerAs/n-type GaAs heterostructures were deposited on 2" undoped semi-insulating GaAs wafers by the AP-MOCVD method at 650C with TMGa, AsH3, TMAl, and SiH4 gases. The n-type GaAs conduction layers were doped with Si to the target concentration of about 2×10\ulcornercm\ulcorner. The Al content was targeted to x=0.5 and the thicknesses of Al\ulcornerGa\ulcornerAs layers were targeted from 0 to 40 nm. In order to investigate the electrical characteristics, an array of Schottky diodes was built on the heterostructures by the lift-off process and Al thermal evaporation. Among the key results of this experiment, the deep level electron traps at 0.742~0.777 eV and 0.359~0.680 eV were observed in the heterostructures; however, only a 0.787 eV level was detected in n-type GaAs samples without the Al\ulcornerGa\ulcornerAs overlayer. It may be concluded that the 0.787 eV level is an EL2 level and that the 0.742~0.777 eV levels are related to EL2 and residual oxygen impurities which are usually found in MOCVD GaAs and Al\ulcornerGa\ulcornerAs materials grown at 630 660C. The 0.359~0.680 eV levels may be due to the defects related with the al-O complex and residual Si impurities which are also usually known to exist in the MOCVD materials. Particularly, as the Si doping concentration in the n-type GaAs layer increased, the electron trap concentrations in the heterostructure materials and the magnitude of the C-V hysteresis in the Schottky diodes also increased, indicating that all are intimately related.ated.

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A study on the characteristics and crystal growth of GaSb (GaSb결정 성장과 특성에 관한 연구)

  • 이재구;오장섭;정성훈;송복식;문동찬;김선태
    • Electrical & Electronic Materials
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    • v.9 no.9
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    • pp.885-890
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    • 1996
  • Undoped p-type and Te doped n-type GaSb crystals were grown by the vertical Bridgman method. The lattice constant of the GaSb crystals was 6.096.+-.000373.angs.. The carrier concentration, the resistivity, and the carrier mobility measured by the van der Pauw method were p.iden.8*1016 c m3 , .rho..iden.0.20 .ohm.-cm, .mu.p .iden.400c m2 V1 se c1 for p-type, n.iden.1*1017 c m3 , .rho..iden.0.15 .ohm.-cm, .mu.n .iden.500c m2 V1 se c1 for n-type at 300K. In case of treatment with metal ion of R u+3, P t+4, the carrier concentration, resistivity and carrier mobility of the GaSb crystals were p.iden.2*1017 c m3 , .rho..iden.0.08.ohm.-cm, .mu.p .iden.420c m2 V1 se c1 for p-type, n.iden.2.5*1017 c m3 , .rho..iden.0.07.ohm.-cm, .mu.n .iden.520c m2 V1 se c1 for n-type respectively. GaSb crystals had a tendency to lower resistivity and higher mobility, for surface treatment with metal ion effectively diminished surface recombination centers.s.

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