Enhanced Quad-Band WO3 Antennas with 1.46 THz Cutoff Frequency via Indium Nanosheets between Stacked Layers

Abstract

Herein, stacked films of WO3 separated by indium nanosheets are fabricated as quad-band antennas suitable for high-frequency applications. The amorphous WO3 films and indium nanosheets are coated onto each other using the thermal evaporation technique under a high vacuum pressure of 10 5 mbar. The stacked layers of Pt/WO3/In/WO3/Pt are structurally and electrically characterized. The tunneling-type quad-band antennas are tested in the driving frequency domain of 0.01–1.80 GHz and a low signal amplitude of 0.10 V. It is observed that the insertion of indium nanosheets between layers of WO3 remarkably increases the width of the tunneling barrier from 55 to 70 nm without altering the tunneling barrier height. This also enhances the cutoff frequency at a quad-band frequency of 1.80 GHz from 10 GHz to 1.46 THz and increases the return loss values from ≈5 to 21 dB. A widely tunable cutoff frequency extending from 0.30 GHz to 1.46 THz can be obtained based on the selected driving signal frequency. The microwave-controlling features of the Pt/WO3/In/WO3/Pt devices, with their high cutoff frequency and high power transmission ratios at the quad-band frequency, make them attractive for 6G technology.