• Title/Summary/Keyword: Edge-defined Film-fed growth

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Crystal growth of yttrium vanadate by the EFG technique

  • Kochurikhin, V.V.;Ivanov, M.A.;Suh, S.J.;Yoon, D.H.
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.11 no.5
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    • pp.203-206
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    • 2001
  • The applicability of shaped growth of yttrium orthovanadate was approved by successful growth of rod-like single crystals with the rectangular shape. Nd-doped single crystals with content of $Nd^{3+}$ ions of 1,2,3,5 atomic % in the starting melt were grown by the EFG technique with the size up to $10^{*}10mm$ in section and up to 85 mm in length. For the testing of the multiple growth of the orthovanadates, two and three Nd-and Yb-doped $YVO_{4}$ single crystals were grown by the EFG technique simultaneously up to 110 mm in length.

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Characterization of epitaxial layers on beta-gallium oxide single crystals grown by EFG method as a function of different crystal faces and off-angle (EFG 법으로 성장시킨 β-Ga2O3 단결정의 다양한 결정면, off-angle에 따른 epitaxial layer의 특성 분석)

  • Min-Ji Chae;Sun-Yeong Seo;Hui-Yeon Jang;So-Min Shin;Dae-Uk Kim;Yun-Jin Kim;Mi-Seon Park;Gwang-Hee Jung;Jin-Ki Kang;Hae-Yong Lee;Won-Jae Lee
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.34 no.4
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    • pp.109-116
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    • 2024
  • β-Ga2O3 is a representative ultra-wide bandgap (UWBG) semiconductor that has attracted much attention for power device applications due to its wide-bandgap of 4.9 eV and high-breakdown voltage of 8 MV/cm. In addition, because solution growth is possible, it has advantages such as fast growth rate and lower production cost compared to SiC and GaN [1-2]. In this study, we have successfully grown Si-doped 10 mm thick Si-doped β-Ga2O3 single crystals by the EFG (Edge-defined Film-fed Growth) method. The growth direction and growth principal plane were set to [010] / (010), respectively, and the growth speed was 7~20 mm/h. The as-grown β-Ga2O3 single crystal was cut into various crystal planes (001, 100, ${\bar{2}}01$) and off-angles (1o, 3o, 4o), and then surface processed. After processed, the homoepitaxial layer was grown on the epi-ready substrate using the HVPE (Halide vapor phase epitaxy) method. The processed samples and the epi-layer grown samples were analyzed by XRD, AFM, OM, and Etching to compare the surface properties according to the crystal plane and off-angle.

Characteristics of Sn-doped β-Ga2O3 single crystals grown by EFG method (EFG 법으로 성장한 β-Ga2O3 단결정의 Sn 도핑 특성 연구)

  • Tae-Wan Je;Su-Bin Park;Hui-Yeon Jang;Su-Min Choi;Mi-Seon Park;Yeon-Suk Jang;Won-Jae Lee;Yun-Gon Moon;Jin-Ki Kang;Yun-Ji Shin;Si-Yong Bae
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.33 no.2
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    • pp.83-90
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    • 2023
  • The β-Ga2O3 has the most thermodynamically stable phase, a wide band gap of 4.8~4.9 eV and a high dielectric breakdown voltage of 8MV/cm. Due to such excellent electrical characteristics, this material as a power device material has been attracted much attention. Furthermore, the β-Ga2O3 has easy liquid phase growth method unlike materials such as SiC and GaN. However, since the grown pure β-Ga2O3 single crystal requires the intentionally controlled doping due to a low conductivity to be applied to a power device, the research on doping in β-Ga2O3 single crystal is definitely important. In this study, various source powders of un-doped, Sn 0.05 mol%, Sn 0.1 mol%, Sn 1.5 mol%, Sn 2 mol%, Sn 3 mol%-doped Ga2O3 were prepared by adding different mole ratios of SnO2 powder to Ga2O3 powder, and β-Ga2O3 single crystals were grown by using an edge-defined Film-fed Growth (EFG) method. The crystal direction, crystal quality, optical, and electrical properties of the grown β-Ga2O3 single crystal were analyzed according to the Sn dopant content, and the property variation of β-Ga2O3 single crystal according to the Sn doping were extensively investigated.

Mechanical Behavior of Directionally Solicified (Y2O3)ZrO2/Al2O3 Eurtctic Fibers

  • Park, Deok-Yong;Yang, Jenn-Ming
    • Journal of the Korean Ceramic Society
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    • v.41 no.1
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    • pp.1-8
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    • 2004
  • The microstructural features and mechanical behavior of directionally solidified $(Y_2O_3)ZrO_2/Al_2O_3$ eutectic fibers after extended beat treatment in oxidizing environment were investigated. The fiber was grown continuously by an Edge-defined Film-fed Growth (EFG) technique. The microstructure was characterized using X-Ray Diffraction (XRD) and Scanning Electron Microscopy(SEM). The microstructure of the fiber in the as-fabricated state consists of highly oriented colonv and fine lamellar microstructure along the fiber axis. Tensile strength of the $(Y_2O_3)ZrO_2/Al_2O_3$ eutectic fiber remained unchanged with heat treatment at temperatures between $1200^{\circ}C$ and $1500^{\circ}C$ up to 300h. The weibulls modulus remained fairly constant after extended thermal exposure. The fracture toughness and crack propagation behavior were investigated. The fracture toughness ($K_{1C}$) of the $(Y_2O_3)ZrO_2/Al_2O_3$ eutectic fiber in the as-fabricated state were measured to be 3.6 ${\pm}$ 0.5 MPa${\cdot}m^{1/2}$ by an indentation technique and 2.2 ${\pm}$ 0.2 MPa${\cdot}m^{1/2}$ by assuming elliptical flaw of a semi-infinite solid, respectively. The $(Y_2O_3)ZrO_2/Al_2O_3$ eutectic fiber showed a radial (Palmqvist) crack type and exhibited an orthotropic crack growth behavior under 100 g load.

Characterizations of Microscopic Defect Distribution on (-201) Ga2O3 Single Crystal Substrates ((-201)면 산화갈륨 단결정 기판 미세 결함 분석)

  • Choi, Mee-Hi;Shin, Yun-Ji;Cho, Seong-Ho;Jeong, Woon-Hyeon;Jeong, Seong-Min;Bae, Si-Young
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.35 no.5
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    • pp.504-508
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    • 2022
  • Single crystal gallium oxide (Ga2O3) has been an emerging material for power semiconductor applications. However, the defect distribution of Ga2O3 substrates needs to be carefully characterized to improve crystal quality during crystal growth. We analyzed the type and the distribution of defects on commercial (-201) Ga2O3 substrates to get a basic standard prior to growing Ga2O3 crystals. Etch pit technique was employed to expose the type of defects on the Ga2O3 substrates. Synchrotron white beam X-ray topography was also utilized to observe the defect distribution by a nondestructive manner. We expect that the observation of defect distribution with three-dimensional geometry will also be useful for other crystal planes of Ga2O3 single crystals.

Characterization of EFG Si Solar Cells

  • Park, S.H.
    • Journal of Sensor Science and Technology
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    • v.5 no.5
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    • pp.1-10
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    • 1996
  • Solar cells made of the edge-defined film-fed growth Si are characterized using current-voltage, surface photovoltage, electron beam induced current, electron microprobe, scanning electron microscopy, and electron backscattering. The weak temperature dependence of the I-V curves in the EFG solar cells is due to a voltage variable shunt resistance giving higher diode ideality factors than the ideal one. The voltage variable shunt resistance is modeled by a modified recombination mechanism which includes carrier tunneling to distributed impurity energy states in the band gap within the space-charge region. The junction integrity and the substrate quality are characterized simultaneously by combining I-V and surface photovoltage (SPV) measurements. The diode ideality factors and the surface photovoltages characterize the junction integrity while the SPV diffusion lengths characterizes the substrate quality. Most of the measured samples show the voltage variable shunt resistance although how serious it is depends on the solar cell efficiency. The voltage variable shunt resistance is understood as one of the most important factors of the degradation of EFG solar cells.

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High Voltage β-Ga2O3 Power Metal-Oxide-Semiconductor Field-Effect Transistors (고전압 β-산화갈륨(β-Ga2O3) 전력 MOSFETs)

  • Mun, Jae-Kyoung;Cho, Kyujun;Chang, Woojin;Lee, Hyungseok;Bae, Sungbum;Kim, Jeongjin;Sung, Hokun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.32 no.3
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    • pp.201-206
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    • 2019
  • This report constitutes the first demonstration in Korea of single-crystal lateral gallium oxide ($Ga_2O_3$) as a metal-oxide-semiconductor field-effect-transistor (MOSFET), with a breakdown voltage in excess of 480 V. A Si-doped channel layer was grown on a Fe-doped semi-insulating ${\beta}-Ga_2O_3$ (010) substrate by molecular beam epitaxy. The single-crystal substrate was grown by the edge-defined film-fed growth method and wafered to a size of $10{\times}15mm^2$. Although we fabricated several types of power devices using the same process, we only report the characterization of a finger-type MOSFET with a gate length ($L_g$) of $2{\mu}m$ and a gate-drain spacing ($L_{gd}$) of $5{\mu}m$. The MOSFET showed a favorable drain current modulation according to the gate voltage swing. A complete drain current pinch-off feature was also obtained for $V_{gs}<-6V$, and the three-terminal off-state breakdown voltage was over 482 V in a $L_{gd}=5{\mu}m$ device measured in Fluorinert ambient at $V_{gs}=-10V$. A low drain leakage current of 4.7 nA at the off-state led to a high on/off drain current ratio of approximately $5.3{\times}10^5$. These device characteristics indicate the promising potential of $Ga_2O_3$-based electrical devices for next-generation high-power device applications, such as electrical autonomous vehicles, railroads, photovoltaics, renewable energy, and industry.