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Silicon nanotips fabricated by electron cyclotron resonance plasma etching of silicon wafers are studied by spectroscopic ellipsometry. The structure of the nanotips is composed of columns 100-140 nm wide and spaced by about 200 nm. Ellipsometry data covering a wide spectral range from the midinfrared to the visible are described by modeling the nanotip layer as a graded uniaxial film using the Bruggeman effective medium approximation. The ellipsometry data in the infrared range reveal two absorption bands at 754 and 955 cm-1, which cannot be resolved with transmittance measurements. These bands indicate that the etching process is accompanied with formation of carbonaceous SiC and CHn species that largely modify the composition of the original crystalline silicon material affecting the optical response of the nanotips. OCIS codes: 120.2130, 160.1245, 260.2065, 310.3840.

Crystalline semiconducting sulfide and selenide zeolite analogs were synthesized that possess four-connected, three-dimensional tetrahedral networks built from tetravalent ([M.sup.4+] = [Ge.sup.4+] or [Sn.sup.4+], where M = meta) and trivalent ([M.sup.3+] = [Ga.sup.3+] or [In.sup.3+]) cations. Microporous materials were obtained in all four combinations of [M.sup.4+] and [M.sup.3+], and some of them were thermally stable up to at least 380°C. These materials exhibit framework topologies with pore size ranging from 12 to 24 tetrahedral atoms, high surface area, high framework charge density and ion exchange capacity, and tunable electronic and optical properties., Microporous materials exemplified by aluminosilicate zeolites have large-scale commercial applications ranging from gas separation to petroleum processing (1). For ~50 years, there has been interest in developing porous materials with [...]

A model for Schottky contacts and electron states at the surface of polycrystalline semiconductor films is presented. The dependence of V and N(sub t) on the grain radius is studied.

Nanocrystalline silicon (nc-Si) thin films have potential for solar cells and thin film transistors. Detailed structural analyses of nc-Ci layers are presented, achieved through thermal annealing of sputtered films containing various hydrogen concentrations. Infrared (IR) spectroscopy, x-ray diffraction, Raman scattering and high resolution microscopy were used to investigate the as-deposited and thermally nanocrystallized layers, and the impact of prior presence of hydrogen on the microstructure and properties of thermally nanocrystallized silicon films.

Filament-assisted diamond growth depends on the temperature of CH3, CH4 and C2H2 close to the substrate. Sampling mass spectrometry showed that CH3 used (2 + 1) resonance-enhanced multiphoton ionization (REMPI), CH4 and C2H2 concentrations. Substrate temperature depends on the CH3 REMOI signal, which has an activation energy of approximately 4 plus or minus 1 kcal/mole at low temperatures. It does not affect methane and acetylene, due to the transformation of methyl to methane or ethane on the surface at low substrate temperatures or in the cool gas layer near the substrate.

The high frequency properties of amorphous and polycrystalline wires mounted as conductors in coaxial lines were investigated, by applying a static magnetic field along the wire axis. Peaks were observed in the real part of the impedance, moving to higher frequency with the strength of the static field, typical ferromagnetic resonance behaviour.

Polycrystalline Si(sub1-x)Gex films have thermoelectric properties when highly doped and are compatible with silicon technology. Attempts have been made to improve the figure of merit of Si(sub1-x)Gex bulk alloys by reducing thermal conductivity. If a small amount of GaP is added to SiGe there is a reduction in thermal conductivity and an increase of 30% in the figure of merit. Crystallized amorphous Si(sub1-x)Gex films were highly doped with boron, and their microstructure and transport properties are reported, along with the effect of the Ge content and boron concentrations on the properties.