Yb/WO3/Yb back to back Schottky barriers designed as voltage controlled rectifiers and as microwave resonators

Abstract

Herein, 𝑝 −WO3 thin films coated onto ytterbium thin film substrates are used as active layers to fabricate a back to back Schottky (BBS) barriers. The Schottky contacts and the tungsten oxide active layers are grown by the thermal evaporation technique under a vacuum pressure of 10-5 mbar. The films are structurally, morphologically, optically and electrically characterized. The physical nature of the grown 𝑝 −WO3 layers is amorphous comprising excess oxygen in its composition. Electrically, the BBS devices displayed a biasing dependent current rectification ratio confirming the tunneling type of Schottky barriers. The current conduction are dominated through tunneling barriers of height of ~0.80 eV. The barriers allow hole tunneling within energy barriers of widths of ~45 nm and of 300 nm under reverse and forward biasing conditions, respectively. In addition, the impedance spectroscopy measurements have shown the ability of wide tunability of the resistance and capacitance of the devices resulting in a microwave cutoff frequency exceeding 2.0 GHz. The resistive and capacitive features of the devices in addition to the microwave cutoff frequency spectra nominate the Yb/𝑝-WO3/Yb BBS devices for use as microwave resonators suitable for 4G/5G technologies.