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The reduction of surface "native" oxides from GaAs substrates following reactions with trimethylaluminum ͑TMA͒ precursor is studied using medium energy ion scattering spectroscopy ͑MEIS͒ and x-ray photoelectron spectroscopy ͑XPS͒. MEIS measurements after one single TMA pulse show that ϳ65% of the native oxide is reduced, confirmed by XPS measurement, and a 5 Å thick oxygen-rich aluminum oxide layer is formed. This reduction occurs upon TMA exposure to as-received GaAs wafers.

We report a systematic study of the bias stress effect at semiconductor-dielectric interfaces using singlecrystal organic field-effect transistors as a test bed. A combination of electrical transport and ultraviolet photoelectron spectroscopy suggests that this instability is due to a ground-state ͑i.e., occurring in the dark͒ charge transfer of holes from the accumulation channel of the semiconductor to localized states of a disordered insulator. The proposed model is not semiconductor specific and therefore provides a general analytical description of this instability in a variety of organic and inorganic band semiconductors interfaced with amorphous insulators.

We have developed and used for the first time a soft x-ray interferometer to probe a large laserproduced plasma with micron spatial resolutions.A neonlike yttrium x-ray laser operating at 155 A was combined with a multilayer coated Mach-Zehnder interferometer to obtain electron density profiles in a plasma produced by laser irradiation of a CH target. The measured electron density profile has been compared to hydrodynamic simulations and shows good agreement near the ablation surface but some discrepancy exists at lower densities.

The effect of introducing a multilayer microstructure on the dielectric properties of polymer materials is evaluated in 32- and 256-layer films with alternating polycarbonate (PC) and polyvinylidene-hexafluoropropylene (coPVDF) layers. The permittivity, dielectric loss, dielectric strength, and energy density were measured as a function of the relative PC/coPVDF volume concentrations. The permittivity follows an effective medium model while the dielectric strength was typically higher than that predicted by a volume fraction based weighted average of the components. Energy densities as high as ∼14J∕cm3, about 60% greater than that of the component polymers, are measured for 50% PC/50% coPVDF films.

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Diodes made by (indirectly) evaporating Au on a monolayer of molecules that are adsorbed chemically onto GaAs, via either disulfide or dicarboxylate groups, show roughly linear but opposite dependence of their effective barrier height on the dipole moment of the molecules. We explain this by Au-molecule (electrical) interactions not only with the exposed end groups of the molecule but also with its binding groups. We arrive at this conclusion by characterizing the interface by in situ UPS-XPS, ex situ XPS, TOF-SIMS, and Kelvin probe measurements, by scanning microscopy of the surfaces, and by current-voltage measurements of the devices. While there is a very limited interaction of Au with the dicarboxylic binding groups, there is a much stronger interaction with the disulfide groups. We suggest that these very different interactions lead to different (growth) morphologies of the evaporated gold layer, resulting in opposite effects of the molecular dipole on the junction barrier height.