Herein, tungsten oxide thin films comprising excess oxygen are treated as optical resonator suitable for gigahertz/terahertz applications. WO3 thin films which are prepared by the thermal evaporation technique under a vacuum pressure of 10 -5 mbar are structurally, compositionally and optically evaluated. The amorphous WO3.33 films which showed high transparency permit electronic transitions within an indirect allowed energy band gap of 3.05 eV. The band gap comprised energy band tails of width of 190 meV. Four dominant dielectric resonators centered in the infrared (IR), visible (VIS) and ultraviolet (UV) ranges of light are detected. Analysis of the optical conductivity in accordance with the Drude-Lorentz approaches have shown that the drift mobility of free holes in this amorphous layer can be as large as 5.61 cm 2 /Vs an as low as 1.59 cm 2 /Vs when exposed to IR and UV light signals, respectively. In addition, the gigahertz/terahertz cutoff frequency (𝑓 𝑐𝑜 ) spectra demonstrated 𝑓 𝑐𝑜 values in the gigahertz frequency domain when exposed to IR light. Excitations with light signals in the VIS and UV spectral ranges allow 𝑓 𝑐𝑜 values that extends from 0.7-40.0 THz. The wide range of tunability of the WO3 dielectric resonators nominates them as dielectric lenses suitable for optical communications.

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Herein, Tungsten trioxide-gallium sulfide heterojunctions which are prepared by the thermal evaporation technique under a vacuum pressure of 10-5 mbar are employed as active media to fabricate a multifunctional device. The WO3/Ga2S3 (WG) heterojunctions which are deposited onto Yb substrates and top contacted with Au pads of areas of 1.5× 10 −2 cm2 displayed electronic hybrid device structure composed of two Schottky arms connected to a 𝑝𝑛 junction. The constructed Yb/WG/Au devices showed tunneling diode characteristics with current conduction dominated by thermionic emission and quantum mechanical tunneling. In additions, the capacitance-voltage characteristic curves indicated the formation of PMOS and NMOS under reverse and forwards biasing conditions demonstrating a metal oxide semiconductor fields effect (MOSFET) transistor characteristics. Moreover, the impedance spectroscopy tests on the devices have shown that the device can perform as tunable microwave resonator suitable for 5G technologies. The resonator showed frequency based capacitance tunability and displayed microwave band pass/reject filter characteristics. The microwave cutoff frequency of the Yb/WG/Au band filters reaches 9.65 GHz with voltage standing wave ratios of 1.06 and return loss factor of ~29 dB.