TY - JOUR

T1 - Effect of Sn substitution for Se on dispersive optical constants of amorphous Se-Te-Sn thin films

AU - Dabban, M.A.

AU - Abdelazim, Nema Mohamed Safwat Ibrahim

AU - Abd-Elnaiem, Alaa M.

AU - Mustafa, S.

AU - Abdel-Rahim, M.A.

PY - 2018

Y1 - 2018

N2 - Optical constants of vacuum evaporated thin films in the Se90−xTe10Snx (x = 0, 2.5, 5 and 7.5 at %) system were calculated from reflectance and transmittance data in the wavelength range of 300–2500 nm using Murmann’s equations. The maximum value of refractive index increased and suffered a shift towards the short wavelength as the Sn content increases this behavior can be attributed to increasing the values of cross-linking chains density and decrease tailing. The variations in the real and the imaginary parts of the dielectric constant, the dissipation factor tan(δ), the optical conductivity, the volume, and surface energy loss functions with photon energy have also been reported. The normal dispersion of the refractive index is discussed regarding the single oscillator Wemple-DiDomenico model from which the dispersion parameters were determined. The single oscillator energy, the dispersion energy, the high-frequency dielectric constant, the ratio of free charge carrier concentration to the effective mass, plasma frequency, single oscillator strength and its position are then estimated as a function of alloy composition. It is interesting to note that the increase of Sn content on the parent Se90Te10 is connected to the decreasing covalent nature of the structure. Besides, the presence of such a sharp absorption edge in transmission spectra recommends Se90−xTe10Snx thin films as a good optical filter material.

AB - Optical constants of vacuum evaporated thin films in the Se90−xTe10Snx (x = 0, 2.5, 5 and 7.5 at %) system were calculated from reflectance and transmittance data in the wavelength range of 300–2500 nm using Murmann’s equations. The maximum value of refractive index increased and suffered a shift towards the short wavelength as the Sn content increases this behavior can be attributed to increasing the values of cross-linking chains density and decrease tailing. The variations in the real and the imaginary parts of the dielectric constant, the dissipation factor tan(δ), the optical conductivity, the volume, and surface energy loss functions with photon energy have also been reported. The normal dispersion of the refractive index is discussed regarding the single oscillator Wemple-DiDomenico model from which the dispersion parameters were determined. The single oscillator energy, the dispersion energy, the high-frequency dielectric constant, the ratio of free charge carrier concentration to the effective mass, plasma frequency, single oscillator strength and its position are then estimated as a function of alloy composition. It is interesting to note that the increase of Sn content on the parent Se90Te10 is connected to the decreasing covalent nature of the structure. Besides, the presence of such a sharp absorption edge in transmission spectra recommends Se90−xTe10Snx thin films as a good optical filter material.

KW - Se–Te–Sn

KW - thin film

KW - optical constants

KW - dispersion parameters

U2 - 10.1080/14328917.2017.1323427

DO - 10.1080/14328917.2017.1323427

M3 - Journal article

VL - 22

SP - 324

EP - 332

JO - Materials Research Innovations

JF - Materials Research Innovations

SN - 1432-8917

IS - 6

ER -