P A Thin Indium containing chalcogenide films for sensor applications

P Petkov
2012 Advances in Natural Science: Theory & Applications   unpublished
Chalcogenide glasses of (GeSe 5) 1−x In x with 5,10,15,20 mol % In have been investigated. Some physico-chemical characteristics have been obtained: density (ρ), compactness (δ), molar volume (Vm). The free volume percentage (FVP) has been attained and correlation with the mean coordination number (Z) has been discussed. The number of constraints per atom (Nco) as a function of the average coordination number has been calculated. The correlations between the composition and properties of the
more » ... roperties of the glasses are discussed with the view of structural transformation in the glassy matrix. The processes of vacuum evaporation and condensation in the glassy Ge-Se-In system were investigated. The thin films deposited under the conditions used are amorphous and without 3D defects proved by TEM analysis. The optical spectra of the thin films have been studied with a view to understanding the role of indium on the film behavior. An optical characterization method, based on the transmission and the reflection spectra at normal incidence of uniform, thin films, has been used to obtain the thicknesses and optical constants corresponding to the as-deposited and annealed samples. The dispersion of the refractive index is discussed in terms of the single-oscillatorWemple-Di Domenico model. The absorptionedges aredescribedusingboththe Urbach rule andthe 'nondirect transition' model proposed by Tauc. The variations in the refractive index, the bandgap, and the oscillation energy ofthe films after annealing are discussedwith respect to rearrangement of themain structure units.