Surface topographic study of chalcogenide thin films of GexSb(As)₄₀-xS₅₀Te₁₀ glasses.
The surface topography and fractal properties of GexSb(As)40-xS50Te10 (x=10, 20, 27 at.%) films, evaporated onto glass substrates, have been studied by atomic force microscopic imaging at different scales. The surface of the chalcogenide films is smooth (<5 nm roughness), isotropic and having some particular differences in texture. All films are self-similar with Mean Fractal Dimension in the range of 2.25-2.63. The films with GexSb40-xS50Te10 composition are more uniform in terms of surface morphology (grains structure) than those with GexAs40-xS50Te10 composition for which the film surface exhibits a superimposed structure of large particles at x=10 and 20 at.%.
Evaluation of basic physical parameters of quaternary Ge–Sb-(S,Te) chalcogenide glasses
New quaternary chalcogenide GexSb40� xS50Te10 (x = 10, 20 and 27 at.%) and GexSb40� xS55Te5 (x = 20 and 27 at.%) glasses have been synthesized and the compositions have been characterized applying prompt gamma-ray activation analyses, neutron diffraction, and material density measurements. Using the experimental data, the basic physical parameters, such as average atomic volume, packing density, compactness, average coordination number, number of constrains, average heat of atomization and cohesive energy, of the synthesized glasses are evaluated and the results are discussed in a function of glass composition.
Optical properties of Ge-Sb-Te chalcogenides
Abstract We have used RF sputtering to grow amorphous films of GeTe, Sb 2 Te 3 , Ge 2 Sb 2 Te 5 , and Ge 2 Sb 2 Te 7 , and employed photothermal deflection spectroscopy (PDS) to characterize the optical absorption in these films. The PDS technique can measure the optical band gap, the exponential ‘band tails’, and the absorption due to deep defects in these materials. The gross features of the absorption of amorphous Ge 2 Sb 2 Te 7 and Ge 2 Sb 2 Te 5 are independent of the substrate temperature from about 290 K to 300 K. The optical band gaps (as measured at α  = 10 4  cm −1 ) of amorphous Ge 2 Sb 2 Te 5 , and Ge 2 Sb 2 Te 7 are all about 1.0 eV, although the absorption does depend slightly on the growth rate at room temperature. The band gaps of amorphous Sb 2 Te 3 and GeTe are about 0.8 and 1.0 eV, respectively, consistent with previously published results.