Abstract
Magnesium selenide thin films are coated onto glass and semitransparent Pt substrates (nanosheets) by the vacuum evaporation technique under a vacuum pressure of 10(-5) mbar. The effect of Pt nanosheets of thicknesses of 100 nm on the structural, compositional, optical, and electrical properties of MgSe is explored. It is found that platinum nanosheets enhance the light absorbability in the visible and infrared ranges of light. They slightly redshift the energy bandgap and decrease the dielectric constant. The strong interaction between Pt and MgSe increases the electrical conductivity by five orders of magnitude. Pt forms shallow impurity levels in the energy bandgap of MgSe allowing the tunneling process at the Pt/MgSe interfaces. Practically, a Pt/MgSe/Pt tunneling type device is fabricated and tested by the microwave impedance spectroscopy technique. It is found that Pt/MgSe/Pt devices can exhibit resonance-antiresonance and negative capacitance effects which are important in electronic circuits as parasitic capacitance cancelers, signal amplifiers, and noise reducers. In addition, evaluation of the cutoff frequency spectra has shown the ability of using the Pt/MgSe/Pt devices as microwave resonators appropriate for 5G/6G technologies. A cutoff frequency larger than 70 GHz can be achieved by imposing ac signal of amplitude of 0.10 V.