Growth and Characterization of Vacuum Evaporated MgSe Thin Films

Herein, thin films of magnesium selenide are thermally grown in a vacuum deposition (VD) system onto glass substrates under a vacuum pressure of 10^–5 mbar. The films are structurally, morphologically, compositionally, and optically characterized. It is observed that MgSe thin films coated by the VD technique are composed of polycrystalline MgSe_1.07 (a = 5.149 Å, space group \(Fm3m\)) and MgSe_1.96 (a = 6.514 Å, space group \({P}_{3-a}\)) cubic phases. The films displayed an average roughness value of 13 nm. They also exhibited a direct energy band gap of 2.54 eV and an indirect band gap of 3.34 eV. In addition, detailed studies of the dielectric properties, optical conductivity, and terahertz cutoff frequency spectra showed the ability of MgSe thin films to perform as a dielectric material. High dielectric constant values are reached in the near-infrared range of light. As optical conductors, the films displayed one IR, two visible, and two ultraviolet light oscillators showing a maximum plasmon frequency of 8.19 GHz in the UV range. The drift mobility of these oscillators varied in the range of 4.57–9.67 cm²/Vs. Moreover, the terahertz cutoff frequency for these oscillators varied in the range of 11–175 THz proofing the suitability of MgSe films for terahertz technology issues.