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Stephen K Oleary - One of the best experts on this subject based on the ideXlab platform.

Kazuhide Kumakura - One of the best experts on this subject based on the ideXlab platform.

  • minority carrier diffusion length in gan dislocation density and Doping Concentration dependence
    Applied Physics Letters, 2005
    Co-Authors: Kazuhide Kumakura, Toshiki Makimoto, Naoki Kobayashi, Tamotsu Hashizume, Takashi Fukui, Hideki Hasegawa
    Abstract:

    We investigated the minority carrier diffusion length in p- and n-GaN by performing electron-beam-induced current measurements of GaN p–n junction diodes. Minority electron diffusion length in p-GaN strongly depended on the Mg Doping Concentration for relatively low dislocation density below 108cm−2. It increased from 220to950nm with decreasing Mg Doping Concentration from 3×1019to4×1018cm−3. For relatively high dislocation density above 109cm−2, it was less than 300nm and independent of the Mg Doping Concentration. On the other hand, the minority hole diffusion length in n-GaN was shorter than 250nm and less affected by the dislocation density and Si Doping Concentration. We discuss the Doping-Concentration and dislocation-density dependence of minority carrier diffusion length.

T Honma - One of the best experts on this subject based on the ideXlab platform.

  • universal optimal hole Doping Concentration in single layer high temperature cuprate superconductors
    Superconductor Science and Technology, 2006
    Co-Authors: T Honma, P H Hor
    Abstract:

    We argue that in cuprate physics there are two types, hole content per CuO2 plane (Ppl) and the corresponding hole content per unit volume (P3D), of hole- Doping Concentrations for addressing physical properties that are two-dimensional (2D) and three-dimensional (3D) in nature, respectively. We find that superconducting transition temperature (Tc) varies systematically with P3D as a superconducting "dome" with a universal optimal hole-Doping Concentration P opt. 3D = 1.6 × 10 21 cm 3 for single-layer high temperature superconductors. We suggest that P opt. 3D determines the upper bound of the electronic energy of underdoped single-layer high-Tc cuprates.

  • universal optimal hole Doping Concentration in single layer high temperature cuprate superconductors
    arXiv: Superconductivity, 2006
    Co-Authors: T Honma, P H Hor
    Abstract:

    We argue that in cuprate physics there are two types, hole content per CuO$_2$ plane ($P_{pl}$) and the corresponding hole content per unit volume ($P_{3D}$), of hole-Doping Concentrations for addressing physical properties that are two-dimensional (2D) and three-dimensional (3D) in nature, respectively. We find that superconducting transition temperature ($T_c$) varies systematically with $P_{3D}$ as a superconducting \textquotedblleft $dome$\textquotedblright with a universal optimal hole-Doping Concentration $P_{3D}^{opt.}$ = 1.6 $\times$ 10$^{21}$ cm$^{-3}$ for single-layer high temperature superconductors. We suggest that $P_{3D}^{opt.}$ determines the upper bound of the electronic energy of underdoped single-layer high-$T_c$ cuprates.

Poppy Siddiqua - One of the best experts on this subject based on the ideXlab platform.

D Abukay - One of the best experts on this subject based on the ideXlab platform.

  • investigation of the variation in weak link profile of yba2cu3 xagxo7 δ superconductors by ag Doping Concentration
    Solid State Communications, 2004
    Co-Authors: Mustafa Tepe, I Avci, H Kocoglu, D Abukay
    Abstract:

    Abstract The effect of Ag Doping Concentration on the microstructure, transport properties and weak-link profile of YBa 2 Cu 3− x Ag x O 7− δ bulk superconducting compound was investigated through resistance–temperature ( R – T ), ac magnetic susceptibility ( χ − T ), scanning electron microscope (SEM), X-ray diffraction (XRD) and the critical current density ( J c ) versus applied magnetic field ( J c − B ) measurements. We used the additive method with cationic ratio of x =0.1−0.4 for the YBCO-Ag system. The change in the silver Doping Concentration slightly affected the transition temperatures ( T c,zero ), whereas, the critical current densities ( J c ) of the samples and their magnetic field ( B ) dependencies were noticeably affected. The improvement on the microstructural properties of YBCO bulk superconductors was observed in SEM analysis, the J c values increased and their magnetic field dependencies decreased with the increasing of Ag Concentration up to x =0.2. As well as the current transport properties. Ag Doping up to a certain amount produces texturing that gives rise to a modification in the weak-link profile resulting in an enhanced strength of flux pinning which causes an increase in the current carrying capacity.

  • investigation of the variation in weak link profile of yba2cu3 xagxo7 δ superconductors by ag Doping Concentration
    Solid State Communications, 2004
    Co-Authors: Mustafa Tepe, I Avci, H Kocoglu, D Abukay
    Abstract:

    Abstract The effect of Ag Doping Concentration on the microstructure, transport properties and weak-link profile of YBa 2 Cu 3− x Ag x O 7− δ bulk superconducting compound was investigated through resistance–temperature ( R – T ), ac magnetic susceptibility ( χ − T ), scanning electron microscope (SEM), X-ray diffraction (XRD) and the critical current density ( J c ) versus applied magnetic field ( J c − B ) measurements. We used the additive method with cationic ratio of x =0.1−0.4 for the YBCO-Ag system. The change in the silver Doping Concentration slightly affected the transition temperatures ( T c,zero ), whereas, the critical current densities ( J c ) of the samples and their magnetic field ( B ) dependencies were noticeably affected. The improvement on the microstructural properties of YBCO bulk superconductors was observed in SEM analysis, the J c values increased and their magnetic field dependencies decreased with the increasing of Ag Concentration up to x =0.2. As well as the current transport properties. Ag Doping up to a certain amount produces texturing that gives rise to a modification in the weak-link profile resulting in an enhanced strength of flux pinning which causes an increase in the current carrying capacity.