Variable angle spectroscopic ellipsometry (VASE) has been used in the photon energy range 1.25–5.0 eV to study the structure and optical properties of cerium dioxide (CeO₂) films. Both amorphous and highly oriented crystalline films were grown on sapphire by rf magnetron sputtering. The crystallinity, chemical structure, and surface morphology of the films were studied by x‐ray diffraction, x‐ray photoelectron spectroscopy, and atomic force microscopy, respectively. The measured VASE spectra on a series of films with different thicknesses were analyzed by using multiple optical models. In this way, the complex refractive index N=n+ik of CeO₂, the film thicknesses, and the surface roughness of the different films could be determined. The ellipsometrically deduced refractive index spectrum was observed to be strongly dependent on the film structure. Highly oriented crystalline CeO₂ films exhibited a higher refractive index and a higher band gap energy than the amorphous film. The surface roughness of the crystalline films increased with film thickness. The optical dispersion relations have also been analyzed by line‐shape fitting with a modified Lorentz oscillator model.

Experimental and ab initio computational methods are employed to conclusively show that ScN is a semiconductor rather than a semimetal; i.e., there is a gap between the N $2p$ and the Sc $3d$ bands. Previous experimental investigators reported, in agreement with band structure calculations showing a band overlap of 0.2 eV, that ScN is a semimetal while others concluded that it is a semiconductor with a band gap larger than 2 eV. We have grown high quality, single crystalline ScN layers on MgO(001) and on TiN(001) buffer layers on MgO(001) by ultrahigh vacuum reactive magnetron sputter deposition. ScN optical properties were determined by transmission, reflection, and spectroscopic ellipsometry while in-situ x-ray and ultraviolet valence band photoelectron spectroscopy were used to determine the density of states (DOS) below the Fermi level. The measured DOS exhibits peaks at 3.8 and 5.2 eV stemming from the N $2p$ bands and at 15.3 eV due to the N $2s$ bands. The imaginary part of the measured dielectric function ${\varepsilon }_2$ consists of two primary features due to direct X- and Γ-point transitions at photon energies of 2.7 and 3.8 eV, respectively. For comparison, the ScN band structure was calculated using an ab initio Kohn–Sham approach which treats the exchange interactions exactly within density-functional theory. Calculated DOS and the complex dielectric function are in good agreement with our ScN valence-band photoelectron spectra and measured optical properties, respectively. We conclude, combining experimental and computational results, that ScN is a semiconductor with an indirect $\Gamma –X$ bandgap of $1.3\pm 0.3\mathrm{eV}$ and a direct X-point gap of $2.4\pm 0.3\mathrm{eV}.$

One hundred years ago Michelson discovered circular polarization in reflection from beetles. Today a novel Mueller-matrix ellipsometry setup allows unprecedented detailed characterization of the beetles' polarization properties. A formalism based on elliptical polarization for description of reflection from scarab beetles is here proposed and examples are given on four beetles of different character: Coptomia laevis – a simple dielectric mirror; Cetonia aurata – a left-hand narrow-band elliptical polarizer; Anoplognathus aureus – a broad-band elliptical polarizer; and Chrysina argenteola – a left-hand polarizer for visible light at small angles, whereas for larger angles, red reflected light is right-handed polarized. We confirm the conclusion of previous studies which showed that a detailed quantification of ellipticity and degree of polarization of cuticle reflection can be performed instead of only determining whether reflections are circularly polarized or not. We additionally investigate reflection as a function of incidence angle. This provides much richer information for understanding the behaviour of beetles and for structural analysis.

The electrical and optical properties of carbon-nitride ${\mathrm{CN}}_x$ films $\text{(0⩽x⩽0.25)}$ deposited by unbalanced reactive magnetron sputtering from a graphite target in mixed ${\mathrm{Ar/N}}_2$ discharges at a substrate temperature of 350 °C have been investigated. Pure C films exhibit a dark conductivity at room temperature of 25 ${\Omega }^{\text{−1}} {\mathrm{cm}}^{\text{−1}},$ which grows up to 250 ${\Omega }^{\text{−1}} {\mathrm{cm}}^{\text{−1}}$ for ${\mathrm{CN}}_x$ films with N content of 20%. For ${\mathrm{CN}}_x$ films, temperature-dependent conductivity measurements suggest that two electron conduction processes exist in the investigated temperature range $\text{130<T<300}$ K. Under white-light illumination, photoconductivity is observed. The film optical properties obtained from spectroscopic ellipsometry measurements between 1.24 and 5 eV indicate a semimetallic behavior with a large amount of ${\mathrm{sp}}^2$ bonds in the material. The measured electrical and optical properties of the films are related to the apparent film microstructure and bonding nature. Electron microscopy show that the addition of ${\mathrm{N}}_2$ in an Ar discharge leads to a transformation from amorphous to a fullerene-like microstructure consisting of curved, frequently intersecting, and highly in-plane oriented basal lattice planes.

2H–AlN(0001) layers have been grown on Si(111) by reactive magnetron sputtering from an Al target in Ar+N2 gas mixtures at temperatures Ts=400–900 °C. Variations in reactive gas consumption, target voltage, and current–voltage characteristics versus nitrogen partial pressure were used to determine deposition parameters required to yield stoichiometric AlN with growth rates ≥2 μm h−1. High-resolution cross-sectional transmission electron microscopy (XTEM) analyses of films grown at 900 °C showed that the initial 6–8 monolayers were (111)-oriented cubic 3C before transforming to the (0001)-oriented 2H polytype. The epitaxial relationship was found by XTEM and x-ray diffraction (XRD) to be 2H–AlN(0001)//3C–AlN(111)//Si(111) with 2H–AlN[12̄10]//3C–AlN[110]//Si[110]. High-resolution XRD ω−2Θ and ω rocking curve widths for films grown at Ts=900 °C were 70 and 500 arc sec, respectively, the lowest values yet reported.