Properties of (Glass, Pb)/MgSe Interfaces Designed as Terahertz Band Filters

Abstract

Herein, thin films of MgSe (300 nm) are deposited onto glass and semitransparent Pb (150 nm) substrates by the thermal evaporation technique under a vacuum pressure of 10⁻⁵ mbar. The films are structurally, morphologically, compositionally, and optically characterized. It is found that Pb substrates induced the formation of single phase of MgSe against a mixture of MgSe and MgSe₂. Lead substrates improved the light absorbability in the infrared (IR) range of light. Pb substrates also red-shifted and blue-shifted the direct and indirect band gap of MgSe by 0.62 eV and 0.10 eV, respectively. The dielectric dispersion analyses have shown that Pb substrates are more effective in the visible and IR ranges of light. When Pb/MgSe films are treated as band filters, they showed wide range of tunability of the terahertz cutoff frequency. The Pb/MgSe interfaces are found good candidates as terahertz band filters sensitive to IR-850 nm lasers which are used in communication technology. Optical oscillators of this wavelength performed within scattering time of 0.50 fs and exhibited drift mobility of 4.69 cm²/Vs. In addition, Drude-Lorentz analyses which targeted finding optoelectronic information about Pb/MgSe have shown the ability of using Pb/MgSe interfaces in thin film transistors, ultraviolet photo-detection, and terahertz technologies.