Pseudodielectric dispersion in As2Se3 thin films

In this work, the X-ray diffraction, energy dispersive X-ray spectroscopy and the spectral ellipsometry techniques are employed to investigate the structural, pseudo-optical and pseudodielectric properties of arsenic selenide thin films. The stoichiometric films which are prepared by thermal evaporation technique are found to prefer the amorphous nature of growth. While the pseudo-absorption coefficient spectra display strong absorption bands at 1.84, 1.81, 1.41 and 1.13 eV, the preferred pseudo-optical transitions happens within a direct forbidden energy band gap of 1.80 eV. In addition, the real part of the pseudodielectric spectra displays three strong resonance peaks at critical energy value of 2.33, 1.90 and 1.29 eV. Modeling of the imaginary part of the pseudodielectric constant spectra in accordance with the Drude-Lorentz approach resulted in the existence of six linear oscillators. The response of arsenic selenide to elliptically polarized light signals has shown that the films exhibit drift mobility, free electron concentration, and plasmon frequency values in the ranges of 0.21-43.96 〖cm〗^2/Vs, 1.90-58.0×〖10〗^19 〖cm〗^(-3) and 5.8-32.0 GHz, respectively. The optical conductivity parameters for As2Se3 film nominates it as promising candidates for the fabrication of tunneling diodes suitable for microwaves filtering up to 32.0 GHz and as thin film transistors.