Insight on the optoelectronic properties of novel quaternary Ge–Se–Tl–Sb non-crystalline glassy alloy films for optical fiber sensing devices

A. M. Ismail; E. G. El-Metwally

doi:10.1140/epjp/s13360-024-05012-6

2024 Impact factor 2.9

EPJ PLUS - Condensed Matter and Complex Systems

Open Access

Eur. Phys. J. Plus (2024) 139: 211
https://doi.org/10.1140/epjp/s13360-024-05012-6

Regular Article

Insight on the optoelectronic properties of novel quaternary Ge–Se–Tl–Sb non-crystalline glassy alloy films for optical fiber sensing devices

A. M. Ismail and E. G. El-Metwally^b

Department of Physics, Faculty of Education, Ain Shams University, 11566, Cairo, Egypt

^b eg_elmetwally@yahoo.com

Received: 5 October 2023
Accepted: 16 February 2024
Published online: 4 March 2024

Abstract

Chalcogenide glass (Ge_0.1Se_0.7Tl_0.2)₈₅Sb₁₅ is synthesized in bulk form by the melt quenching method and thermally evaporated as thin films. The amorphous character of the studied films is examined by XRD analysis. The values of refractive index ( $n$ $$n$$ ) and extinction index ( $k$ $$k$$ ) are estimated from transmittance $T (λ)$ $T(\lambda )$ data using Swanepoel’s method and are found to be thickness independent. The values of the indirect optical band gap ( $E_{g}^{opt}$ ${E}_{g}^{{\text{opt}}}$ ) and Urbach tail ( $E_{U}$ ${E}_{{\text{U}}}$ ) energies are 1.164 eV and 0.176 eV, respectively. The optical $σ_{opt}$ ${\sigma }_{{\text{opt}}}$ and electrical $σ_{elec}$ ${\sigma }_{{\text{elec}}}$ conductivities of (Ge_0.1Se_0.7Tl_0.2)₈₅Sb₁₅ films increase while the penetration depth $P_{d}$ ${P}_{{\text{d}}}$ decreases with photon energy ( $h ν$ $h\nu$ ). The Wemple-DiDomenico (WDD) oscillator model calculates optical parameters such as single-oscillator $E_{o}$ ${E}_{{\text{o}}}$ and strength $E_{d}$ ${E}_{{\text{d}}}$ energies, lattice dielectric constant $ε_{L}$ ${\varepsilon }_{{\text{L}}}$ and ratio $N / m^{*}$ ${\text{N}}/{{\text{m}}}^{*}$ . The calculated values of third-order susceptibility $χ^{(3)}$ ${\chi }^{(3)}$ and nonlinear index of refraction $n_{2}$ ${n}_{2}$ are 6.34 × 10^–12 and 3.76 × 10^–11 $esu$ ${\text{esu}}$ . Dielectric constant $ε^{'}$ ${\varepsilon }^{\prime}$ and loss $ε^{''}$ ${\varepsilon }^{{\prime}{\prime}}$ decrement with frequency and increment with temperature. The ac conductivity $σ_{ac}$ ${\sigma }_{{\text{ac}}}$ increases with frequency and temperature, which is proportional to $ω^{s}$ ${\omega }^{s}$ and the exponent $s$ $$s$$ decreases with temperature. The obtained results of $σ_{ac}$ ${\sigma }_{{\text{ac}}}$ and $s$ $$s$$ are interpreted via the correlated barrier hopping (CBH) model. Values of the density of localized states $N (E_{F})$ $N\left({E}_{{\text{F}}}\right)$ are enhanced with frequency and temperature. The results obtained suggest that $ε^{'}$ ${\varepsilon }^{\prime}$ , $ε^{''}$ ${\varepsilon }^{{\prime}{\prime}}$ , $σ_{ac}$ ${\sigma }_{{\text{ac}}}$ and $N (E_{F})$ $N\left({E}_{{\text{F}}}\right)$ are improved by decreasing the film thickness. These research results emphasize the composition’s applicability for several optical potential applications, like optical fiber sensing devices, photo-detectors, and narrow band optical filters.

© The Author(s) 2024

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