We have investigated the electrical resistivity of (0001)-oriented Tin+1ACn (A = Si, Ge, Sn, n = 1–3) thin films deposited by magnetron sputtering onto Al2O3(0001) substrates at temperatures ranging from 500 to 950 °C. Four-point-probe measurements show that all films are good conductors with resistivity values of ∼21–51 μΩ cm for Ti–Si–C films, ∼15–50 μΩ cm for Ti–Ge–C films, and ∼46 μΩ cm for Ti2SnC. We find a general trend of decreasing resistivity with decreasing n for the Ti–Si–C and Ti–Ge–C systems due to the increased metallicity obtained with increasing density of A-element layers. We also show that crystalline quality and competitive growth of impurity phases affect the measured resistivity values. The effect of a given impurity phase largely depends on its location in the sample. Specifically, a TiCx layer in the center of the film constricts the current flow and results in an increased measured resistivity value. However, TiCx transition or seed layers at the substrate–film interface as well as surface segregation of Ge and Ti5Ge3Cx (for Ti–Ge–C) have only little effect on the measured resistivity values. For the Ti–Sn–C system, the resistivity is mainly influenced by the segregation of metallic Sn, yielding a wide spread in the measured values ranging from 20–46 μΩ cm, in the order of increased film purity.
Spherical colloidal photonic supraparticle systems or assemblies (SCAs) are investigated as a model system for confined optical and photonic components. Simulations of the reflection spectrum to calculate their photonic and optical properties for different parameter constellations are compared with experimental studies by microreflectance spectroscopy (𝜇RS) on SCAs fabricated by inkjet in-flight deposition, proving the existence of a dual-band reflection spectrum originating from the supraparticle system. Finite-difference time-domain (FDTD) calculations are employed to verify these findings as a function of structural parameters. Both, theory and experiment, show a double reflection peak for the SCAs and agree well in the variation of position and shape, scaling clearly with the packing density of the SCAs. Reducing this parameter from 0.6 to 0.3, the higher-wavelength reflection maximum decreases in intensity and increases in width but keeps its spectral position. The lower-wavelength reflection maximum decreases in intensity, increases in width and shows a red shift. The results clearly indicate that aspects of disorder decisively contribute to the particular spectral photonic properties of the supraparticle system which are usually related to order in photonic crystals. This finding can stipulate novel, tailor-made nanostructured optical components such as low-dimensional micro resonators and waveguides.
W and WN films with thicknesses of less than one monolayer up to some nanometers were deposited by magnetron sputtering. The samples were transferred after deposition immediately into an analysis chamber without breaking the vacuum to avoid oxide formation and contamination. Analysis was done by means of XPS for elemental and bonding state characterization and angle-resolved XPS (ARXPS) for nondestructive depth profiling. Phase formation and morphology were studied during the first stages of layer growth. Influences of the residual gas atmosphere are discussed.
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