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Amorphous boron-hydrogen alloys (9 to 24 at % H) have been prepared and optical properties determined. In the ir, the only bands observed involving H are the B-H stretch at 2560 cm−1 and the B-H bend at 1108 cm−1; no evidence is found for bands associated with BH2 groupings or H three-center bonds. In the visible-near uv, the ϵ2 spectrum for the sample with 9 at % H has a broad maximum near 5eV with a peak value of 6. With increasing H content, both optical gap and ϵ2 peak move to higher energies, while the ϵ2 peak value and refractive index decrease.

The inability of experimentalists to observe small‐angle x‐ray scattering from single‐phase liquids and amorphous solids has been considered, by many workers in the field, to invalidate a crystallite model for these materials. In this work we calculate the intensity of small‐angle x‐ray scattering from two crystallite models which are designed to yield upper bounds to the actual scattering. The calculated upper bounds are, in general, considerably lower in intensity than the scattering from isolated particles. The results are extremely sensitive to the density and average crystallite size of the sample, so that general conclusions about the observability of such scattering cannot be made. The particular case of vitreous SiO2, which was examined experimentally by Warren and Weinberg, has been studied in detail. For this case, the calculated scattering intensity is of the same order of magnitude as that observed by these authors. Thus, it is concluded that the failure to observe small‐angle scattering from ...

Three potential applications for the “ladder” siloxanes in photonic technologies are discussed. These are: (1) as a silica fiber cladding material for which a silica fiber core-siloxane cladding index depression (Δn) of 0.04 is observed; (2) as a fiber coating material to provide mechanical and environmental protection for which a siloxane coated silica core fiber is observed to have improved properties over a fiber coated with an epoxy-acrylate or linear siloxane. Thus, the ladder siloxane can serve a dual coating/cladding function; and (3) as the passive lightguiding element in planar optoelectronics for which the index depression (Δn), as compared to silica, is 0.04 for the cured siloxane. 0.02 for a fenestrated silica obtained by removing the organic component from the siloxane, or values between 0.02 and 0.0 obtained by sintering this fenestrated silica.

The optical properties of undoped and P‐doped silicon prepared by low‐pressure chemical vapor deposition were measured by spectroscopic ellipsometry over the energy range 3.0–6.0 eV. A marked effect of material microstructure is observed. Approximate values of the density deficit and of the volume fractions of crystalline and amorphous material are estimated as components of the microstructure by comparing measured spectra to those synthesized from constituent spectra in the Bruggeman effective‐medium approximation.

Initial air oxidaton rates and limiting oxide thickness of plasma‐deposited amorphous silicon (a‐Si(H)) films are at least an order of magnitude less than those of single‐crystal silicon. Spectral change resulting from either chemically forced or long–term natural oxidation followed by HF stripping show that oxidation proceeds by consuming inhomogeneously distributed silicon, thereby leading to an increased surface roughness and density deficit in the film.

This chapter surveys transitions between the viscous liquid state and the glass, phase-separated, or crystalline states and some of the uses of these transitions in altering the structure and properties of solids. In addition to its intrinsic interest, the liquid ↔ glass transition is important for kinetically limiting the other two types of transition. It is these limiting effects which make possible the formation of quite unique structures in the transitions. We will begin by reviewing the liquid ↔ glass transition.

The optical properties of polysilicon on insulating SiO2 were measured by spectroscopic ellipsometry over the energy range 3.0 to 6.0 eV. Spectra were obtained for films as-deposited and after irradiation with an Ar ion laser (focused to a 50μm spot diameter) at 6.0, 7.0 or 7.5 watts. We observed monotonic changes in both ε1 and ε2 with increasing incident power even though the power density was high enough to completely melt the silicon surface in all cases. The changes observed are caused by changes in microstructure; with increasing power the amorphous component decreases and the density increases. Approximate values of the microstructural components are estimated by comparing measured spectra to those synthesized from constituent spectra in the Bruggeman effective medium approximation.