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We report on nanoscale patterning of GaAs (100) semiconductor substrates employing an ion projection through a self-organized stencil mask. The nanostructured mask, formed by ion beam sputtering of a polycrystalline Au film, allows driving the GaAs morphology strongly out of equilibrium. In a second stage, after the stencil mask is removed, we quantitatively follow the dynamical evolution of the forced system toward equilibrium by analyzing the evolution of the power spectral density of the height profiles and their slope and curvature distribution. Strong differences are observed by comparing the relaxation dynamics of GaAs surfaces which tend to smoothen with that of glass, a material which instead tends to non-linearly amplify the pattern once driven out of equilibrium by the stencil mask. [ABSTRACT FROM AUTHOR]

The adjustable photoluminescence (PL) and field electron emission (FEE) properties of boron carbonitride (B–C–N) nanotubes grown under well-controlled conditions are studied systematically. Large-scale highly aligned B–C–N nanotubes are synthesized directly on Ni substrates by the bias-assisted hot filament chemical vapor deposition method. Single-walled B–C–N nanotubes and nanometric B–C–N heterojunctions are obtained by the pulsed-arc-discharge technique and pause-reactivation two-stage process, respectively. It is found that the microstructures, orientations, and chemical compositions of the nanotubes can be controlled by varying growth parameters. The mechanism of the controllable growth is also investigated. Intense and stable PL from the nanotubes is observed in both blue-violet (photon energies 3.14–2.55 eV) and yellow-green bands (photon energies 2.13–2.34 eV) and the emission bands are adjusted by varying the compositions of the nanotubes. FEE properties are also studied and optimized by varying the B or N atomic concentrations in the nanotubes. All these results verify the controllability of the electronic band structure of the B–C–N nanotubes. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Deals with a study that investigated the Schottky barrier height and the thermal stability of nickel on n-type gallium nitride. Use of capacitance-voltage and current-density-temperature methods; Experimental details; Results and discussions.

Studies the growth and characterizations of galliumnitride on silicon carbide substrates with buffer layers. Enhanced electron mobility; Hall measurement and sheet carrier density; Bulk carrier density and lattice constants.

Sintering characteristics and microwave dielectric properties of Mg4Ta2O9-5wt% B2O3 ceramics were investigated. With the sintering temperature increasing in the range of 1100C-1350C, the apparent density, and values increased firstly and then saturated at 1250C with excellent microwave properties: , GHz and ppm/C. Compared to the pure MT ceramics, the B2O3 additives effectively decreased the sintering temperature of MT ceramics and had no detrimental effect on the properties of the MT ceramics due to the liquid phase effect. [ABSTRACT FROM AUTHOR]

Corundum structured Mg4Nb2O9 dielectric ceramics with the excess of MgO were prepared by the sol-gel process and microwave dielectric properties were investigated with the excess of MgO. First, according to the stoichiometric ratio of Mg4Nb2O9 phase formation was studied by means of XRD analysis by adjusting the ratio of Mg/Nb and the ratio was ranging from 0·5 to 2·4. Subsequently, based on phase formation microwave dielectric properties of Mg4Nb2O9 ceramics as a function of ratio of Mg/Nb were obtained depending on phase change. The results showed that when the ratio of Mg/Nb was 2·1, pure phase of Mg4Nb2O9 ceramics could be obtained at 1275°C with excellent microwave dielectric properties of εr = 12·5, Qƒ = 224,000 GHz, τƒ = −42·8 ppm/°C. [ABSTRACT FROM AUTHOR]