Review—The Negative Capacitance of a Novel Structure Au/PPy-MWCNTs/TiO2/Al2O3/p-Si/Al

Abstract

A novel structure of Au/PPy-MWCNTs/TiO2/Al2O3/p-Si/Al is presented for application in electronic devices such as diodes, supercapacitors, energy storage devices, and sensors. The negative capacitance (NC) in this structure appeared at a high frequency of 2 × 107 Hz for all voltages and temperatures, with positive and negative values of −8 × 10–9 to 12 × 10–9 Farad, NC disappeared at frequencies 107, 106, 105 and appeared another time at a frequency of 103, 102 and 10 Hz. Their values were positive and negative values, except at 10 Hz, where the capacitance had negative values only. The conductance at all frequencies, voltages, and temperatures had positive values only, with the values increasing with frequencies increased. The capacitance with lnf at all frequencies, temperatures, and voltages has positive and negative values. From 1/C2 –V the electric parameters such as the width of the depletion layer (Wd), the series resistance (Rs), the surface density of states (NSS), the width of the oxide layer dox, the barrier height (ɸb), the Fermi level (Ef), (Vd), and the acceptor carrier concentration (Na), were calculated.