Preparation and optical dispersion and absorption of Ag-photodoped Ge_xSb_40−xS₆₀(x= 10, 20 and 30) chalcogenide glass thin films

Abstract

We have analysed the effect of silver content on the optical properties of Ag-photodoped amorphous GexSb40−xS60 (with x = 10, 20 and 30 at.%) chalcogenide thin films; the chalcogenide host layers were prepared by vacuum thermal evaporation. Films of composition Agy(GexSb40−xS60)100−y, with y ≲ 10 at.%, were prepared by successively photodissolving about 10 nm thick layers of silver. The film thickness and optical constants have been accurately determined by a refined envelope method, based upon the two envelope curves of the optical-transmission spectrum, obtained at normal incidence. The dispersion of the linear refractive index of the Ag-photodoped chalcogenide films is analysed in terms of the Wemple–DiDomenico single-effective-oscillator model. We have found that the maximum change in the index of refraction, between the Ag-photodoped and the undoped material, is about 0.08, when the Ag-concentration reaches the level of saturation of around 10 at.%. On the other hand, the Tauc gap, , decreases notably, with increasing Ag-content: for instance, in the particular case of x = 10 at.%, the smallest Ge-content, decreases from 1.97 down to 1.67 eV.

Dual action of light in photodarkened Ge–As–S films

“…[15]. Recently, it has been shown [16] also that the irreversible PB in some Ge-As-S films possibly connected with the tailing, cannot be explained only by the decrease of the width of the localized states, respectively, with changes in E u only. To further clarify the relationship between both disorder parameters the changes in the Urbach parameter have been analyzed.…”

Effect of Ge Addition on the Optical Band Gap and Refractive Index of Thermally Evaporated Thin Films

“…This increase in the refractive index may be ascribed to increase of disorder in the structure, change in stoichiometry and internal strain caused with the addition of Ge. The values of n and k at 800 nm (as nearly at this wavelength the spectrum region changes) are given in The optical band gap (E opt g ) has been determined from absorption coefficient data as a function of photon energy, according to the generally accepted "nondirect transition" model for amorphous semiconductors [16], proposed by Tauc [17] …”

Structure-optical property correlations of arsenic sulfide glasses in visible, infrared, and sub-millimeter regions

“…Physically, E 0 is related and proportional to the bond energy of different chemical bonds [26]. It was found for crystalline solids that E d is proportional to the number of nearest cations to the anion as…”