Design and Characterization of (Yb, Al, Cu, Au)/GeO2/C As MOS Field Efect Transistors, Negative Capacitance Effect Devices and Band Pass/ Reject Filters Suitable for 4G Technologies

Abstract

Herein, the effect of Yb, Al, Cu and Au metal substrates on the electrical performance of germanium oxide-based devices is reported. Back-to-back Schottky-type metal-insulator-metal (MIM) electronic devices with the structure (Yb, Al, Cu, Au)/GeO2/C are prepared by vacuum evaporation under a vacuum pressure of 10−5 mbar. Capacitance-voltage characteristic curve analysis on these devices have shown that, while the forward-biased Al/GeO2/C displays NMOS (enhanced N-channel metal oxide semiconductor) characteristics, Cu/GeO2/C and Au/GeO2/C show inverted NMOS and PMOS fields effect transistor (FET) characteristics under forward and reverse biasing conditions, respectively. A large scale (8–737 nm) of depletion width and built-in potentials engineering is possible via metallic substrate selection. In addition, current-voltage characteristic curve analysis have shown that the dominant transport mechanism is by electric field-assisted tunneling through narrow barriers. The only device that showed current rectification was the Yb/GeO2/C device. The absence of the recertification property from the (Al, Cu, Au)/GeO2/C devices is assigned to the large surface roughness of the metal substrates. Analysis of the capacitance, conductance, impedance and reflection coefficient spectra in the frequency domain of 0.01–1.80 GHz have shown that the proposed device structures can exhibit features of negative capacitance effect devices and tunable microwave/radio wave cavities. The observed notch frequency values of the (Yb, Al, Cu, Au)/GeO2/C devices make them suitable for use as bandpass/reject filters suitable for 4G technology.