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.

We report on the successful growth of strained core-shell GaAs/InGaAs nanowires on Si (111) substrates by molecular beam epitaxy. The as-grown nanowires have a density in the order of 108 cm−2, length between 3 and 3.5 μm, and diameter between 60 and 160 nm, depending on the shell growth duration. By applying a range of characterization techniques, we conclude that the In incorporation in the nanowires is on average significantly smaller than what is nominally expected based on two-dimensional growth calibrations and exhibits a gradient along the nanowire axis. On the other hand, the observation of sharp dot-like emission features in the micro-photoluminescence spectra of single nanowires in the 900–1000-nm spectral range highlights the co-existence of In-rich enclosures with In content locally exceeding 30 %.

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Fourier Transform Infrared (FTIR) reflectance spectroscopy has been implemented as a non-destructive, non-invasive, tool for the optical characterization of a set of c-plane InN single heteroepitaxial layers spanning a wide range of thicknesses (30–2000 nm). The c-plane (0001) InN epilayers were grown by plasma-assisted molecular beam epitaxy (PAMBE) on GaN(0001) buffer layers which had been grown on Al2O3(0001) substrates. It is shown that for arbitrary multilayers with homogeneous anisotropic layers having their principal axes coincident with the laboratory coordinates, a 2 × 2 matrix algebra based on a general transfer-matrix method (GTMM) is adequate to interpret their optical response. Analysis of optical reflectance in the far and mid infrared spectral range has been found capable to discriminate between the bulk, the surface and interface contributions of free carriers in the InN epilayers revealing the existence of electron accumulation layers with carrier concentrations in mid 1019 cm−3 at both the InN surface and the InN/GaN interface. The spectra could be fitted with a three-layer model, determining the different electron concentration and mobility values of the bulk and of the surface and the interface electron accumulation layers in the InN films. The variation of these values with increasing InN thickness could be also sensitively detected by the optical measurements. The comparison between the optically determined drift mobility and the Hall mobility of the thickest sample reveals a value of rH = 1.49 for the Hall factor of InN at a carrier concentration of 1.11 × 1019 cm−3 at 300° Κ.

Silicon was implanted with 2 MeV O+ ions with doses covering the range from 1×1017 to 2×1018 O+ normalcm −2 , at an implantation temperature of 700°C. Subsequently, samples were capped and annealed at 1300°C. Infrared reflectance spectroscopy has been used in order to characterize the as‐implanted and annealed samples. The optical modeling of the multilayer structures and the data reduction procedure are given in detail. The thickness, chemical composition, crystallinity, interface macroscopic roughness, and refractive index profiles are quantified. It is shown that infrared reflectance spectroscopy is a quick, nondestructive, analytical, and precise method for characterizing high energy separation by implantation of oxygen (SIMOX) structures. Cross correlation with H+ beam Rutherford backscattering/channeling, secondary ion mass spectroscopy, and cross‐sectional transmission electron microscopy results, gives good agreement. The formation of oxide in the high energy region follows the same basic rules as in the standard SIMOX case. No anomalous oxygen diffusion was observed during annealing and a buried layer formed during annealing even for the lowest dose. It is found that the microstructure of the annealed samples is strongly dependent on the implantation conditions such as beam current density and that even for the highest dose of 2×1018 O+ cm− , a continuous stoichiometric silicon dioxide layer has not formed after annealing.