Determination of allowed transitions types and the optical parameters of Se–Ge–Ag chalcogenide films

Shakra, A.M.; El-Metwally, E.G.

doi:10.1140/epjb/e2018-90273-7

Cited by 9 publications

(3 citation statements)

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“…The second part, for a < -10 cm , 4 1 which is known as the Urbach tail. The Urbach energy E U relates to the transition from tail expansion in occupied extended states (E.S) of the valance band (V.B) to empty tail states in the conduction band (C.B).…”

Section: Refractive Index (N) and Extinction Coefficient (K)mentioning

confidence: 99%

“…A new generation of optical materials is established by combining chalcogens such as Se and Te with other chalcogenide elements [1,2] and metals of groups 13, 14 and 15 that are characterized by their low optical absorption, high transparency in the middle and far IR spectral range, hydrophobicity and reversible phase transformation. The relatively high atomic mass of both Se and Te tends to generate low phonon energy in amorphous chalcogenide glass (ChGs) networks and hence provides a broad optical transmission window in the IR region [3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

“…) and (b) shows the photon energy dependence of s opt and the skin depth W , respectively. It is obvious that, the higher s opt and the smaller W values for GIS-Te than for GIS-Se films, see table2, may be attributed to the high absorption of photons by GIS-Te films, resulting in electron excitations[1,23,26,27,30].…”

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confidence: 99%

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Impact of Se and Te addition on optical characteristics of ternary GeInSb chalcogenide films as promising materials for optoelectronic applications

El-Metwally¹,

Atyia²,

Ismail³

2022

Phys. Scr.

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The present study investigates the linear and non-linear optical characteristics of non-crystalline quaternary Ge15In5Sb5Se75 (GIS-Se) and Ge15In5Sb5Te75 (GIS-Te) chalcogenide thin films. The values of transformation temperatures determined by differential thermal analysis (DTA), such as glass transition T_g and crystallization T_c temperatures, are 524.3 and 639.6 K for GIS-Se and 503.6 and 542.0 K for GIS-Te. The calculated values of glass forming ability (GFA) and thermal stability (H) for GIS-Se are higher than those for GIS-Te. The transmittance T(λ) and reflectance R(λ) spectrophotometric measurements in the UV-vis. wavelength range (400 - 2500 nm) are used to estimate the index of refraction n and extinction coefficient k. Tauc’s extrapolation model was used to determine both Urbach tail (E_U) and optical band gap (E_g^opt) energies. The values of (E_U) are 0.416, 0.526 eV and (E_g^opt) are 1.83, 1.31 eV with indirect allowed transitions for GIS-Se and GIS-Te, respectively. The optical conductivity σ_opt increased as photon energy (hν) increased, and it was enhanced in the presence of Te than Se addition. The analysis of the index of refraction (n) is used to evaluate the dispersion energy E_d, the high frequency dielectric constant ε_∞, the oscillator strength S_0, the lattice dielectric constant ε_L, the ratio N⁄m^* and the optical electronegativity ∅_opt, which were found to be higher in GIS-Te than those in GIS-Se composition. The volume (VELF) and surface (SELF) energy loss functions were found to be increased with increasing (hν) and the presence of Te. Furthermore, the calculated values of nonlinear optical susceptibility χ^((3)) and nonlinear index of refraction n_2 for GIS-Se and GIS-Te are 0.195  10-12, 2.44  10-11 esu and 0.868  10-12, 10.19  10-11 esu, respectively. The detailed outcomes show that the studied film samples are suitable for various optical applications.

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Section: Refractive Index (N) and Extinction Coefficient (K)mentioning

confidence: 99%