Plasmonic interactions at the Pb/SeO2 interfaces designed as terahertz/gigahertz optical receivers

Abstract

Herein semitransparent lead substrates of thicknesses of 200 nm are employed as plasmonic in- terfaces to enhance the optoelectronic performance of SeO2 thin films. Pb/SeO2 interfaces are fabricated by the physical vapor deposition technique under a vacuum pressure of 10-5 mbar. The structural analyses showed that Pb substrates can induce the evolution of tetragonal phase of selenium oxide. The phase comprises 1.27% cubic PbSe in its structure. Surface morphology studies show that Pb substrates prefer formation of grains of sizes of 250 nm resulting from the accumulation of lead crystallites of sizes of 37 nm. Optically, Pb substrates increased the light absorbability in the visible range of light without altering the value of the energy band gap, im- proved the dielectric response by 4% at 1.15 eV and by 40% at 1.87 eV. In addition, Durde- Lorentz modeling of the optical conductivity spectra of SeO2 has shown that Pb plasmonic res- onators increase the plasmon frequency and free carrier density of Pb/SeO2 interfaces allowing it reaching 5 G/6 G technology needs. Moreover, evaluation of the terahertz cutoff frequency spectra indicated the applicability of the Pb/SeO2 as optical receivers responsive to infrared, vis- ible and ultraviolet bands of light at terahertz cutoff frequency values of 17–160 THz. Further- more, the capacitance and conductance spectral studies in the frequency domain of 0.01–1.80 GHz indicated the suitability of Pb/SeO2/C devices as negative conductance sources beneficial for signal amplification in the microwave frequency domain