Optical properties and structure of amorphous (As_0.33S_0.67)_100−xTe_xand Ge_xSb_40−xS₆₀chalcogenide semiconducting alloy films deposited by vacuum thermal evaporation

Abstract

Amorphous films with compositions (As0.33S0.67)100−xTex (x = 0, 1, 5 and 10 at.%) and GexSb40−xS60 (x = 10, 20 and 30 at.%) have been prepared by thermal evaporation. The compositional dependences of their optical properties, with increasing Te and Ge content, respectively, are explained in terms of the modifications occurring in the film structure: Te joins the glassy network through the substitution of S atoms in the AsS3 pyramidal units, to form new AsS2Te mixed pyramidal units, on the one hand, and, on the other hand, there is a presence of GeS4 and S3Ge–GeS3 structural units, when the Ge content is increased. The refractive-index dispersion has been analysed on the basis of the Wemple–DiDomenico single-oscillator approach. It has been found that the refractive index increases in the As–S–Te system, with increasing Te content, while it decreases instead, in the Ge–Sb–S system, with increasing Ge content. The behaviour of the Tauc gap, when the composition of the material is varied, shows, as expected, just the opposite trends.

Analysis of some optical parameters of the glasses of the system Bix(As2S3)100‐x

“…Furthermore, its value for the glass As 2 S 3 is 5.33 ± 0.04 eV [6], which means that the decreasing trend is in full agreement with the results of spectroscopic measurements. The physical meaning of this parameter is related to the energies of different chemical bonds [6].…”

“…As the optical band gap for the composition As 2 S 3 is 2.5 eV [6], it is evident that already with the first composition its value decreases to a significant extent. With the further increase in the content of dopant atoms, the trend of decrease continues.…”

“…The calculated values for the parameter E e are given in Table 1. The value of this parameter for the glass As 2 S 3 is 81 MeV [6], and hence the greatest effect of the increase in the disorder of the structure corresponds just to the composition with the lowest content of the dopant. Further increase in the Bi content has, as a consequence, structural ordering which corresponds to that in the matrix As 2 S 3 .…”

First-principles study of the lattice dynamics of Sb2S3

“…They hold great promise as photovoltaic converters and thermoelectric cooling devices 4,5 due to their small direct bandgaps, high thermoelectric power, and high absorption coefficient in the visible region 6,7 . There is also a surge of interest in using Sb 2 S 3 as a solid-state semiconductorsensitized solar cell to replace the inorganic dye in dye-sensitized solar cells 7,8 .…”

Focused ion beam etched ring-resonator in CVD-grown Ge-Sb-S thin films

“…In particular, germanium antimony sulphide (Ge-Sb-S) glasses have been intensively investigated because they can form stable ternary glasses within a large glass forming region and offer several properties of interest including high nonlinearity and photosensitivity [4]. The preparation of Ge-Sb-S thin films is usually performed by thermal evaporation techniques [5][6][7] with Ge-Sb-S target materials prepared by seal ampoule and melt-quench method. However, for the first time a direct fabrication method for Ge-Sb-S thin films with variable composition has been demonstrated.…”