Determination of the Refractive Index and Optical Absorption Coefficient of Vapor-Deposited Amorphous AsS Films from Transmittance Measurements

Abstract

The optical transmission spectra of amorphous AsS films of composition As32S68 prepared by thermal evaporation are measured over the 0.3 to 2.0 μm spectral region. A simple straightforward procedure suggested by Swanepoel is applied for determining the index of refraction and layer thickness; the absorption coefficient is derived using the Connell and Lewis formulae based on the interference‐free transmittance. Furthermore, thickness measurements made by a surface profiling stylus are also carried out to cross‐check the results corresponding to the fringe pattern method. The dispersion of n is discussed in terms of the single‐oscillator Wemple and DiDomenico model and the absorption edge is described using the “non‐direct transition” model proposed by Tauc. Finally, the compositional trends of the refractive index, absorption coefficient, and optical band gap in the AsS chalcogenide glass system are analyzed in detail.

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

“…Therefore, one could infer that the increase in E d with increasing arsenic is due to an increase in coordination number (N c ) in the first coordination shell. It has been previously observed in As-S films that E 0 decreases and E d decreases with increasing arsenic content up to 40 at.% arsenic [28]. In this study, this trend was observed in E d but not in E 0 .…”

Determination of the optical constants of thermally evaporated amorphous As40S60, As35S65 and As30S70 using transmission measurements

“…Therefore by adding S to As 2 S 3 the average bond strength of the compound increases, which causes E opt g to increase. The values of E opt g gradually decrease towards the stoichometric composition As 40 S 60 , Ramirez-Mato et al [15] have observed similar compositional dependence in the As-S cholegoenide glass system.…”

“…This figure can be seen that the values of refractive index gradually increase towards the stoichometric composition As 40 S 60 . Ramirez-Mato et al [15] have observed similar compositional dependence in the As-S cholegoenide glass system. Now, the values of n 2 can be fitted to a reasonable function such as the two-term Cauchy dispersion relationship, nðlÞ ¼ a þ b=l 2 , which can be used for extrapolation the whole wavelengths [16] (see Fig.…”

“…al. [15]). In the amorphous As-S system it is reasonable to assume the proportionality E d $N c in which N c % 3 for As 40 S 60 and 2 for sulfur.…”

Quantum cascade lasers tuned by amorphous As 2 S 3 claddings

“…Studies of the dependence of the optical properties of spin-coated As 2 S 3 films on illumination soon followed [9,10]. Particularly interesting is that that the index of refraction was found to depend strongly on wavelength [11] and to permanently increase by several percent after illumination [12,13].…”