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/TiO₂/Al2O₃/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 × 10⁷ and 10⁷ 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 /TiO₂/Al₂O₃/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.

The aim of the paper has always been to explore the possibility of constructing new electronics devices based on Au/CNT/TiO₂/SiO₂/p-Si/Al multi-layers structure highlighting the appearance of negative dielectric constant (ε′) and dielectric loss tangent (ε′) at low frequencies in the range 5000–10 Hz. We have investigated the structural, electrical, and dielectric properties of this structure using different techniques like SEM, XRD pattern, Raman spectroscopy, I-V, and C-V measurements. At various temperatures, frequencies, and voltages, we present a detailed analysis of the dielectric constant and dielectric loss tangent. The highest dielectric constant combined with the lowest dielectric loss tangent would improve the use of Au/CNT/TiO₂/SiO₂/p-Si/Al structures in various electronic applications such as diodes, energy storage, and supercapacitor devices. In this study, the maximum dielectric constant values were around 4000, with dielectric loss tangents ranging from 0.08 to 0.32 at high and mid-frequency ranging from (2 × 10⁷ − 10⁵ Hz). The Col-Col diagram of ε′ as a function of ε′ of Au/CNT/TiO₂/SiO₂/p-Si/Al was also investigated.

Ultrathin MoO₃ semiconductor nanostructures have garnered significant interest as a promising nanomaterial for transparent nano- and optoelectronics, owing to their exceptional reactivity. Due to the shortage of knowledge about the electronic and optoelectronic properties of MoO₃/n-Si via an ALD system of few nanometers, we utilized the preparation of an ultrathin MoO₃ film at temperatures of 100, 150, 200, and 250 °C. The effect of the depositing temperatures on using bis(tbutylimido)bis(dimethylamino)molybdenum (VI) as a molybdenum source for highly stable UV photodetectors were reported. The ON–OFF and the photodetector dynamic behaviors of these samples under different applied voltages of 0, 0.5, 1, 2, 3, 4, and 5 V were collected. This study shows that the ultrasmooth and homogenous films of less than a 0.30 nm roughness deposited at 200 °C were used efficiently for high-performance UV photodetector behaviors with a high sheet carrier concentration of 7.6 × 10¹⁰ cm⁻² and external quantum efficiency of 1.72 × 10¹¹. The electronic parameters were analyzed based on thermionic emission theory, where Cheung and Nord’s methods were utilized to determine the photodetector electronic parameters, such as the ideality factor (n), barrier height (Φ₀), and series resistance (R_s). The n-factor values were higher in the low voltage region of the I–V diagram, potentially due to series resistance causing a voltage drop across the interfacial thin film and charge accumulation at the interface states between the MoO₃ and Si surfaces.