Tuned high dielectric constant, low dielectric loss tangent with positive and negative values for PPy/MWCNTs/TiO ₂ /Al ₂ O ₃ /n-Si

The paper presents structural and dielectric properties of Polypyrrole-MWCNTs/TiO2/Al2O3/n-Si emphasizing that one of the superior characteristics is the appearance of negative dielectric constant and dielectric loss tangent at both high and low frequencies. It may worth mentioning that the need to develop electronic devices based on new materials combination has motivated the development of such structures as supercapacitors and diodes. The structural characterization of PPy-MWCNTs/TiO2/Al2O3/n-Si was investigated using X-ray diffraction, FTIR, Raman spectroscopy, and scanning electron microscope. The oxide film thickness (dox), the density of state (NSS), admittance (Ym), electric field (Em), depletion layer width (Wd), and ΔΦb (eV) were examined using the C−2 − V relationship. At low frequencies, the values of Wd, Φb increase, however as frequency rises, the Wd, Nss, and Rs decrease. The dielectric constant (ɛ`) takes only negative values at a high frequency of 2x107 Hz, whereas it takes both negative and positive values at frequencies of 107, 100, and 10 Hz. The dielectric loss tangent (tanδ) has positive and negative values at frequencies 107, 106, 100, and 10 Hz.