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    Effects of Pb nanosheets substrates on the optical and electrical properties CrSe thin films
    (Physica Scripta, 2023) Aljaloud, Amjad Salamah M.; Qasrawi, Atef Fayez; Alfhaid, Latifah Hamad Khalid
    Herein the effects of lead nanosheets substrates on the optical and electrical properties of chromium selenide thin films were studied. Chromium selenide thin films were grown by vacuum thermal evaporation technique onto glass and 100 nmthick lead nanosheets substrates. The effects of Pb nanosheets on the structural, morphological, compositional, optical and electrical properties was explored. While films grown onto glass substrates showed compositional stoichiometry forming CrSe2 phase those coated onto Pb substrates preferred the growth CrSe phase. Both films were of amorphous structure and exhibited direct and indirect allowed optical transitions. Pb nanosheets enhanced the optical absorption of chromium selenide in the visible and ultraviolet ranges of light. Formation of films onto Pb nanosheets resulted in band gaps and band tails narrowing and decreased the room temperature electrical conductivity (s) as well. Deep analyses of the s - T variations in the range of 25–340 Kshowed that the electronic transport is dominated by the thermal excitation and variable range hopping of charge carriers. It was observed that Pb nanosheets increased the average hopping energy and hopping range, decreased the density of localized states near the Fermi level and increased the degree of state disorder. The features of glass/CrSe2 and Pb/CrSe films are promising for using then in optoelectronic technology
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    Growth and characterization of chromium selenide thin films for optoelectronic applications
    (Optical and Quantum Electronics, 2023) Aljaloud, Amjad Salamah M.; Qasrawi, Atef Fayez; Alfhaid, Latifah Hamad Khalid
    Herein amorphous and stoichiometric CrSe2 thin films are obtained by the thermal deposition (TD) technique under a vacuum pressure of 10?5 mbar. The films are structurally, morphologically, optically and dielectrically characterized. It is observed that CrSe2 thin films grown by TD technique exhibit optical excitations within direct and indirect allowed energy band gaps of 2.60 eV and 3.19 eV, respectively. The amorphous CrSe2 thin films contained a wide range of exponential band distribution presented by Urbach energy width of 2.24 eV. In addition in contrast to the chemical bath deposition technique which produced Cr7Se8 films of low dielectric constant ( ), the TD technique revealed high dielectric constant values up to 11.9 for CrSe2 films. Moreover, the Drude-Lorentz modeling of the imaginary part of the dielectric constant spectra revealed drift mobility values in the range of 0.70–6.45 cm2/Vs. The plasmon frequency varied in the range of 5.42–8.33 GHz. Furthermore, analysis of the terahertz cutoff frequency ( ) spectra have shown that CrSe2 thin films exhibit values in the range of 3.30–40.0 THz. The features of CrSe2 thin films deposited by the thermal evaporation technique are promising semiconductor layers suitable for 6G and terahertz technology applications.
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    Optical properties of chromium-selenide films designed for terahertz applications
    (Optik, Eylul 2023) Aljaloud, Amjad Salamah M.; Qasrawi, Atef Fayez; Alfhaid, Latifah Hamad Khalid
    Herein the effects of indium substrates on the properties of chromium selenide thin films are reported. Chromium selenide thin films and indium substrates are prepared by the thermal evaporation technique under a vacuum pressure of 10?5 mbar. It is observed that indium sublayers alters the atomic stoichiometry of chromium selenide. It induces the formation of Cr2Se3 phase instead of CrSe2 phase which grow onto glass substrates. Both of the glass/CrSe2 and In/Cr2Se3 films displayed direct and indirect energy band gaps. The respective gaps are 2.60 eV and 3.19 eV and 2.25 eV and 2.83 eV. The Urbach tails states exhibited a width of 2.24 eV in glass/CrSe2 and showed value of 0.85 eV in In/Cr2Se3. In addition a light absorbability enhancement of more than 45% is reached at the In/Cr2Se3 interfaces in the visible range of light. Moreover, as terahertz resonators, In/Cr2Se3 films showed larger optical conductivity. It also displayed a spectral terahertz cutoff frequency in the range of 3.0–35 THz. Furthermore, when utilized as terahertz resonators, In/Cr2Se3 films demonstrate heightened optical conductivity and a spectral terahertz cutoff frequency ranging from 3.0 to 35 THz. Analyzing these terahertz oscillators using Drude-Lorentz models reveals that the density of free charge carriers increases with higher oscillator energy, while the drift mobility of these carriers within the terahertz resonators varies between 1.10 and 3.09 cm²/Vs. The array of features showcased by In/Cr2Se3 thin films, including their performance as terahertz resonators, positions them as strong contenders for applications in optical and terahertz technologies.