Design of Au/Cdbr2/Au as Negative Capacitance Devices and as Band Filters Suitable for 4G Technologies

Abstract

Herein, cadmium bromide thin film devices are designed for possible use in communication technology. The 1.0 mμ thin layer of CdBr2 is sandwiched between two Au (1.0 mμ thick) layers using the thermal evaporation technique under a vacuum pressure of 10-5 mbar. The Au/CdBr2/Au devices are structurally morphologically and electrically characterized. It is observed that the hexagonal cadmium bromide exhibits large lattice mismatches with cubic Au substrates. The randomly distributed nano- rod like grains is accompanied with average surface roughness of ~26 nm. When an ac signal of low amplitude is imposed between the terminals of the Au/CdBr2/Au devices, a negative capacitance effect in the frequency domain of 10-1800 MHz is observed. In addition, analysis of the impedance spectra in the same domain has shown that the device behaves as band pass/stop filters suitable for 4G technology. The microwave based standard analysis of the Au/CdBr2/Au band filters have shown that it displays a notch (cof) frequency of 2.0 GHz. The cutoff frequency at cof reaches 7.86 GHz. The features of the Au/CdBr2/Au devices nominate it for use as microwave resonators and as negative capacitance devices suitable for; 4G technology, noise reduction and for parasitic capacitance cancellation.