The spectral dependence of the refractive index n and extinction coefficient k of chemical-vapor-deposited (CVD) silicon oxide film on silicon wafer has been determined. The results are used to calculate spectral absorbances for 0.1–2 μm thick oxide films with unchanged structure. The dependence on thickness of the position of Si-O stretching ( vM) has been investigated. The main factor influencing the frequency is the transmission factor at the air/film and film/substrate boundaries. In the limit of d → 0, vM corresponds to the maximum of the Im (ε) function.

This method was developed to determine the complex infrared optical constant of a single free-standing partially absorbing plate as wellas a thin solid film eposited on it. The method is based on exact formulas for normal transmittance T and near-normal reflectance R of the substrate as well as the film-substrate double layer. Coherent multiple reflections throughout the film and incoherent multiple reflections in the substrate as well as the intensity losses on the rough surface are taken into account. The influence of various data on the solution of the inverse problem is discussed by a contour map study. The method is explained using examples of both- and single-side-polished silicon wafers where the transmission and reflection roughness factor functions H(T),H(R) are determined for the rough surface. The thin-film example has been the silicon oxide film formed on the single-side-polished silicon substrate by chemical vapor deposition.

The structure of the ionic glasses (KCl) x (BiCl 3 ) 1−x , where x = 0.35, 0.40, 0.45, has been measured at 20 K by using neutron diffraction. The results show that BiCl 3 units exist as the predominant structural motifs at all compositions, give a Bi-Cl nearest-neighbour distance of 2.53(2)Å, and an angle Cl-Bi-Cl of 89(2) • . The nearest-neighbour K-Cl correlations occur at about 3.1Å. The first sharp diffraction peak observed in the total structure factors is attributed to Bi-Bi correlations and the shift in its position to smaller scattering vector values with increased x is attributed to an enlarged separation of the BiCl 3 units with enhanced KCl content. † Now at: Department of Physics, University of Bath, Bath BA2 7AY, UK. ‡ Following Madden and Wilson (1996), we regard an 'ionic' system as one whose properties are reproduced by an interaction model based on discrete closed-shell ions with integer charges, and a 'covalent' system as one whose interactions arise from the formation of chemical bonds involving the sharing of pairs of electrons between atoms. Many properties conventionally attributed to 'covalency' may be explained in terms of 'ionic' interactions provided that effects such as polarization, compression and deformation are taken into explicit account.

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