Enhanced properties of indium thin films by stacking with platinum nanosheets designed for advanced terahertz/gigahertz applications

Abstract

Herein stacked layers of metallic indium (150 nm) and platinum (50–250 nm) thin films are fabricated as a terahertz/gigahertz filters. Indium thin films are produced by the thermal evaporation technique under a vacuum pressure of 10− 5 mbar and coated with Pt nanosheets using the ionic coating technique. It is observed that Pt nanosheets increased the light transmittance and reflectance in In/Pt films. In/Pt stacked layers displayed lower; dielectric constant, optical conductivity and terahertz cutoff frequency values as compared indium thin slabs. In/Pt stacked layers is found appropriate as tunable terahertz filters. In addition, the Drude-Lorentz analyses on these optical layers have shown that In/Pt stacks exhibit plasmon frequency values (8.7–17.3 GHz) that make them suitable for 5G/6G technology as band filters. The optical conductivity parameters including the drift mobility, free electron density and scattering time at femtosecond level are also determined. As a confirming technique an ac signals propagating with driving frequency in the range of 0.01–0.50 GHz is imposed between the terminals of In/Pt stacked layers. It is shown that the microwave cutoff frequency is widely tunable achieving values of 40 GHz at driving frequency of 0.50 GHz. The features of the In/Pt stacked layers are promising as they show properties of tunable terahertz/gigahertz filters.