Novel negative capacitance, conductance at high and low frequencies in Au/Polypyrrole –MWCNT composite /TiO2/Al2O3/n-Si structure

Abstract

The paper presents a new approach based on the appearance of negative capacitance (NC) at high and low frequencies; previously, researchers agreed that NC only occurred at high or low frequencies. For the first time, we synthesized Au/polypyrrole/MWCNT composite/TiO _2 /Al2O _3 /n-Si/Al structure for use in electronic and supercapacitor applications. The structural, electrical, and dielectric properties were investigated by x-ray diffraction, FTIR, Raman spectroscopy, I-V, and C-V measurements. The results revealed that for all working voltages and temperatures, negative capacitance and conductance occurred at high frequencies between 2 × 10 ^7 and 10 ^7 Hz. Similarly, the phenomena of negative capacitance occurred at low frequencies (100, 10) Hz. The capacitance-voltage experiments were used to perform the analysis of the variation of capacitance and conductance with frequency, voltage, and temperature. The polypyrrole, MWCNT composite /TiO _2 /Al _2 O _3 /n-Si structure exhibits diode behavior and has a high rectification ratio. I-V measurements were used to investigate ideality factors, barrier height, series and shunt resistance#, and rectification ratio.

Keywords

• multiwall carbon nanotube (MWCNT)
• polymer oxide semiconductor (POS)
• heterojunction diode
• I-V characterization
• C-V characterization