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Epitaxial n-ZnO/MgO/TiN/n+-Si heterostructured light-emitting diodes have been fabricated. The epitaxial growth of MgO/TiN on Si(111) was established by pulsed laser deposition, which was further employed as a buffer layer for epitaxial growth of ZnO layer by metal-organic chemical-vapor deposition. Good epitaxial quality was found using high-resolution x-ray diffraction and transmission electron microscopy. A strong wide electroluminescence band, ranging from 350 to 850 nm and centered at ∼530 nm, was observed from the diode when a positive voltage was applied on Si substrate. The diode exhibited a linear light-output-current characteristic with an injection current up to 192 mA. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations are performed to investigate the bending behavior of tubular graphite cones (TGCs). The second-generation reactive bond-order potential and four different van der Waals potentials are used to describe bonding and nonbonding atomic interactions, respectively. It is shown that the bending behavior is insensitive to the choice of the van der Waals potentials. An increase in the cone apex angle of TGCs moderately improves the bending stiffness due to the low shear resistance between the nanotube walls. A TGC with a high cone apex angle is preferred to a TGC with a low cone apex angle in terms of bending stiffness and stress level. It is also shown that an increase in the diameter of the innermost nanotube effectively increases the bending stiffness of TGCs. [ABSTRACT FROM AUTHOR]

Bulk waves radiated into an anisotropic half-space by an interdigital transducer are studied theoretically. The mechanical displacements of excited waves are obtained by asymptotic evaluation of an integral whose singularities give rise to both Rayleigh surface waves and angularly focused bulk waves. By applying the analysis to singly rotated Y cuts of quartz with propagation normal to the x axis, it is shown that the orientation and width of the main lobe are very sensitive to frequency and crystal orientation. [ABSTRACT FROM AUTHOR]

Dense, crack-free, uniform, and homogeneous (RE[sub 2]O[sub 3])[sub 0.08](ZrO[sub 2])[sub 0.92] (RE=Sc, Y) nanocrystalline thin films were fabricated by a simple sol-gel method and characterized by impedance studies. At temperatures beyond 600 °C, the electrical conductivity of (Sc[sub 2]O[sub 3])[sub 0.08](ZrO[sub 2])[sub 0.92] and (Y[sub 2]O[sub 3])[sub 0.08](ZrO[sub 2])[sub 0.92] nanocrystals in pure cubic phase was ten times higher than that of the corresponding bulk materials. The decrease of grain boundary resistance related to interfacial effect is predominately responsible for the electrical conductivity enhancement. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]