Au/CdBr2/SiO2/Au Straddling-Type heterojunctions designed as microwave multiband pass filters, negative capacitance transistors and current rectifiers

Abstract

Herein, nanosheets of SiO2 of thicknesses of 25-100 nm are employed to enhance the performance of Au/CdBr2 Schottky barriers. The Au/CdBr2/SiO2/Au straddling type heterojunction devices is prepared by the thermal evaporation technique. It is observed that SiO2 layers enhances the crystallinity of CdBr2 through increasing the crystallite sizes and decreasing the defect density, stacking faults and microstrain by 50%, 56%, 32% and 34%, respectively. A work function of 6.38 eV is determined from the temperature dependent electrical resistivity measurements of p−type CdBr2. In addition, it was observed that, when coated with 50 nm thick SiO2, the Au/CdBr2/SiO2/Au straddling type transistors can reveal high current rectification ratios of 6.9× 102 at low biasing voltages in the range of 0.06-0.30 V. The alternating current signals analysis in the microwave range of spectra indicated that the current conduction mechanism is dominated by the correlated barrier hopping and quantum mechanical tunneling. It was observed that the Au/CdBr2/SiO2/Au devices exhibit negative effect accompanied with resonance-antiresonance in the capacitance spectra. Moreover, the microwave cutoff frequency which reaches ~165.1 GHz and the magnitude of reflection coefficient spectra has shown that the device under study can perform as multiband pass/stop filters suitable for wire/wireless communication applications including 3G/4G technologies.