Self-directed growth of AlGaAs core-shell nanowires for visible light applications

Al(0.37)Ga(0.63)As nanowires (NWs) were grown in a molecular beam epitaxy system on GaAs(111)B substrates. Micro-photoluminescence measurements and energy dispersive X-ray spectroscopy indicated a core-shell structure and Al composition gradient along the NW axis, producing a potential minimum for carrier confinement. The core-shell structure formed during the growth as a consequence of the different Al and Ga adatom diffusion lengths.Comment: 20 pages, 7 figure

Interplane Transport and Superfluid Density in Layered Superconductors

We report on generic trends in the behavior of the interlayer penetration depth $\lambda_c$ of several different classes of quasi two-dimensional superconductors including cuprates, Sr$_2$RuO$_4$, transition metal dichalcogenides and organic materials of the $(BEDT-TTF)_2X$-series. Analysis of these trends reveals two distinct patterns in the scaling between the values of $\lambda_c$ and the magnitude of the DC conductivity: one realized in the systems with a Fermi liquid (FL) ground state and the other seen in systems with a marked deviation from the FL response. The latter pattern is found primarily in under-doped cuprates and indicates a dramatic enhancement (factor $\simeq 10^2$) of the energy scale $\Omega_C$ associated with the formation of the condensate compared to the data for the FL materials. We discuss implications of these results for the understanding of pairing in high-$T_c$ cuprates.Comment: 4 pages, 2 figure

Computed tomography for iodine contrast media detection using energy information measured by a current-mode detector

To exploit the energy information of X-rays in computed tomography (CT), we developed a current-mode detector that gave the energy distribution of incident X-rays. The CT value obtained for a given material in a phantom depended on the X-ray path length through the phantom. To ensure a constant CT value for a given material, we prepared response functions as a function of X-ray path length and applied these response functions in the unfolding process. When using response functions that depended on X-ray path length, the CT values obtained were constant for a given material. In addition, the CT values obtained for iodine contrast media were greater than the values obtained using conventional current CT, especially for higher X-ray tube voltages

PIEZOREFLECTANCE CHARACTERIZATION OF GaAs/AlAs MULTIPLE QUANTUM WELLS

Piezoreflectance characterization has been applied for GaAs/AlAs multiple quantum wells. The room-temperature spectra have revealed sharp reflectance features due to interband transitions in the quantum wells, as well as in the AlAs barrier. The spectral features are described in terms of the strain-induced interband energy shifts

Electronic structure of (111)-GaAsP/AlGaAs strained-layer quantum wells

Surface Science3871-3371-382SUSC

Optical property of a novel (111)-oriented quantum structure

Applied Physics Letters71131840-1842APPL

Energy subtraction computed tomography measured by current-mode detector

For the reduction of exposure dose in contrast media detection with x-ray transmission measurements, the energy measurement of x-rays and the energy subtraction (ES) method have been shown to be effective. To make the ES method applicable, a novel detector for unfolding the x-ray energy distribution was proposed by the authors. As an application of this novel detector, a CT image was reconstructed with ES data and compared with the image reconstructed using electric current data