Optical and dispersion parameters of Ge-Zn-Se glassy films for VIS and FTIR Applications
Awad A. Ibraheem, K.A. Aly
Abstract
Abstract Different <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mi>G</mml:mi> <mml:mi>e</mml:mi> <mml:mi>Z</mml:mi> <mml:mi>n</mml:mi> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> <mml:mrow> <mml:mn>100</mml:mn> <mml:mo>−</mml:mo> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> <mml:mi>S</mml:mi> <mml:msub> <mml:mrow> <mml:mi>e</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> <mml:mspace width="0.25em"/> <mml:mrow> <mml:mfenced close=")" open="(" separators=""> <mml:mrow> <mml:mn>9</mml:mn> <mml:mo>≤</mml:mo> <mml:mi>x</mml:mi> <mml:mo>≤</mml:mo> <mml:mn>25</mml:mn> <mml:mspace width="0.25em"/> <mml:mi>a</mml:mi> <mml:mi>t</mml:mi> <mml:mo>%</mml:mo> </mml:mrow> </mml:mfenced> </mml:mrow> </mml:math> chalcogenide films have been thermally evaporated onto cleaned glass substrates. The film transmission (T) and reflection (R) spectra have been measured over the wavelength spectral range (0.3–2.5 μ m). The composition dependence of the optical band gap ( E g ) has been illustrated and interpreted in the light of the Mott and Davies Model (MDM). The linear correlation between the changes in the optical band gap (ΔE g ) and in the band tail parameter ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="normal">Δ</mml:mi> <mml:msqrt> <mml:mi>B</mml:mi> </mml:msqrt> </mml:math> ) confirmed the disorder’s decrease, which explains the observed increase in E g values with increasing Se concentrations. The dispersion and Sellmeier parameters have been determined and well discussed. A clear blueshift was observed throughout the o bserved decrease in values of λ o and n o and the observed shift of the absorption edge to the short wavelengths. The GZS films are transparent in the visible, near- and far-infrared, which makes these glasses suitable for VIS and infrared applications.