The optical response of coherent thin-film multilayers is often represented with Fresnel coefficients in a 2 x 2 matrix configuration. Here the usual transfer matrix was modified to a generic form, with the ability to use the absolute squares of the Fresnel coefficients, so as to include incoherent (thick layers) and partially coherent (rough surface or interfaces) reflection and transmission. The method is integrated by use of models for refractive-index depth profiling. The utility of the method is illustrated with various multilayer structures formed by ion implantation into Si, including buried insulating and conducting layers, and multilayers with a thick incoherent layer in an arbitrary position.

A generalized matrix method is presented for calculating the optical reflectance and transmittance of an arbitrary thin-solid-film multilayer structure on very thick substrates with rough surfaces and interfaces. We show that the effect of roughness and the influence of incoherently reflected light on the back side of a thick layer can be accounted for with a more general transfer matrix that enables the inclusion of modified complex Fresnel coefficients. Coherent, partially coherent, and incoherent multiply reflected light inside the multilayer structure is treated in the same way. We demonstrate the method by applying it to simulated and experimental reflectance spectra of thin epitaxial Si overlayers on very thick SiO(2) substrates and on a separation by ion implantation of oxygen structure with a SiO(2) buried layer exhibiting substantial roughness on both of its interfaces (Si/SiO(2) and SiO(2)/Si).

Optical absorption measurements of the different phases of In2Se3 are made. The fundamental absorption edge of α‐In2Se3 and γ‐In2Se3 is studied as a function of the temperature. Far‐infrared reflectivity measurements of the three phases α, β‐ and γ‐In2Se3 are also considered and optical parameters are determined from a least‐squares fitting.

The crystal structure of Sb 2 Se 3 has been redetermined with 610 independent reflections, using three-dimensional intensities measured on a computer-controlled Philips PW 1100 single-crystal diffractometer. The structure does not deviate in principle from that proposed by Dönges (1950) and Tideswell, Kruse, Mc Cullough (1957), but it shows interesting details. The cell constants, obtained by least-squares calculation from direct Θ-value measurements on the diffractometer, are: α = 11.7938(9), b = 3.9858(6), c = 11.6478(7) Ä, Ζ = 4; the space group is Pnma. The positional and thermal parameters, with anisotropic temperature factors, were refined by full-matrix, least-squares calculations to a final R = 0.052. Sb 2 Se 3 is isostructural with Sb 2

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