Quantum Effects of Indium/Ytterbium Doping on ZnO-Like Nano-Condensed Matter in terms of Urbach-Martienssen and Wemple-DiDomenico Single-Oscillator Models Parameters

Abstract

Conducting and transparent optical ZnO thin films were deposited on glass substrates by a simple mini spray technique. Alternatively, some of the obtained films were doped with indium and ytterbium at the molar rates of: 1, 2, and 3% (In) and 100, 200, and 300 ppm (Yb). In addition to the classical structural investigations including XRD, microhardness vickers (Hv), and optothermal techniques, thorough optical measurements have been carried out for comparison purposes. The refractive indices and the extinction coefficients of the differently doped layers have been deduced from their transmission-reflection spectra over an extended wavelength range. Analysis of the refractive index data through Wemple-DiDomenico single oscillator model yielded quantum characteristics along with the values of long-wavelength dielectric constant, average oscillator wavelength, average oscillator strength, average oscillator energy and dispersion energy. Real and imaginary parts of dielectric constant have also been used to calculate free carrier plasma resonance frequency, optical relaxation time, and free carriers concentration-to-effective mass ratio. Finally, analysis of Urbach-Martienssen model parameters allowed proposing nanoscale explanations to the divergence about doping-related evolution of Urbach tails, this intriguing item having been intensively discussed in the literature in the last decades.

Influence of Doping on Optical Properties of (CdS:Fe+3)Thin Films Prepared by Chemical Spray pyrolysis

“…The energy gap is calculated when (αhυ 2 = 0) is from the intersection area of the tangent with the ( hυ) axis, so the intersection point represents the energy gap and we note that The values of the optical energy gap (E g opt ) decrease with the increase in the rate of doping because of the formation of the local levels within the energy gap and then increase slightly at the ration of (5%), as in Figure 6. The Extinction coefficient (k o ) was calculated according to the following equation (5) [9].…”

Study Influence of Substrate Temperature on Optical Properties of CdS Thin Films Prepared by Chemical Spray pyrolysis

“…The Extinction Coefficient was calculated according to the following formula [15]: Figure 7. shows the change in the Extinction Coefficient as a function of the wavelength of the thin films (CdS) for the different substrate temperatures.…”

Effect of Composition and Annealing on Structural and Optical Properties of (ZnO)1-X (TiO2)X Thin Films Prepared by Sol-Gel Method

“…Where β is a constant independent of photon energy .The optical energy-gap E g , can be deduced from plots of (αhν) 2 -versus-(photon energy hν), where α is the absorption-coefficient, ν is the frequency of the electromagnetic-wave [26], while values of what is called Urbach energy E u , can be deduced from plots of ln(α)-versus-hν, in accordance with the following relation [27] α= α o exp (hν /E u ) .......... (6).…”