Conduction Mechanism Of Samples Research Articles

The investigation of interlayer (CeO2:PVC) effects on the dielectric features of Au-Si (MS) Schottky barrier diodes (SBDs) using the impedance spectroscopy method

In this research, Au-PVC-Si (MPS1), Au-(CeO2: PVC)-Si (MPS2) Schottky barrier diodes (SBDs) have been grown on n-type silicon (n-Si) with the aim of investigating the frequency dependence and the effect of polymer interlayer on dielectric parameters such as complex dielectric constant (ε = ε′–iε″), ac-conductivity (σ ac), and complex electric-modulus (M = M′ + iM″). For this purpose, the mentioned parameters have been calculated by measuring C/G-f in wide-range frequency (100 Hz–1 MHz) at room temperature for all three diodes and how the effect of PVC and (CeO2: PVC) interlayer on dielectric parameters of Au-Si (MS) has been studied. In the low-frequency range, plot C-f shows a negative capacitance behavior (NC) that causes the dielectric constant to be negative in this frequency range. Such negative behavior can be described using capture and emissions of carriers at interface states. The results of examining the frequency dependence of dielectric parameters showed that these parameters are sensitive to the frequency, especially the low-frequency range, which is due to the surface polarization and interface states. Also, the conduction mechanism of samples was investigated through the slope of the lnσ ac- lnω plot. The σ ac value for all three diodes at low frequencies is almost independent of the frequency, which is related to dc conductivity (σ dc). The slope value of the lnσ ac- lnω plot in the high frequencies was smaller than the unit which can be described by the hopping mechanism. The presence of the PVC and (PVC: CeO2) interlayer in the metal-semiconductor junction has increased the dielectric constant and conductivity of MPS compared to MS-type SBDs.

Cr-substitution effect on structural and electromagnetic properties of Mg-Ni ferrite synthesized via sucrose auto-combustion method

The effect of compositional variation on the structural, and electromagnetic properties of Ni0.5Mg0.5Fe2−xCrxO4 nanocrystalline ferrites (0 ≤ x ≤ 1.0) is presented. The ferrites were prepared by simple and environmental friendly sucrose assisted auto-combustion method with average crystallite size of 30-14 nm. The structure, morphology, magnetic and electrical properties of the samples were studied. XRD evidenced single-phase formation and exhibited a gradual decrease in the lattice parameters with increasing chromium. An appropriate cation distribution was then suggested and discussed based on the obtained structural, magnetic and electrical properties. The obtained results from the present study provided sufficient evidences that the successive replacing of Fe3+ ions by Cr3+ ions in the octahedral sites significantly affect both magnetization as well as the conductivity of the entire system. The ac-conductivity vs. temperature change indicated magnetic transition from ferro- to paramagnetic for samples with Cr-content ≤ 0.6 and a change in the conduction mechanism for samples with Cr-content x ≥ 0.8. The dielectric measurements confirmed these results and showed a gradual decrease with increasing frequency for all the samples.

Barium/Lead‐Rich High Permittivity Glass–Ceramics for Capacitor Applications

Dielectric properties of glass–ceramics containing barium/lead‐based sodium niobates and barium titanate‐based silicates were evaluated for capacitor applications. The glasses were formed by melt‐rolling the respective constituents which were then crystallized by reheating them at higher temperatures. Crystallization schedules were formulated based on differential thermal analysis results. X‐ray diffractometer patterns indicated that the samples were highly crystallized. Microstructure and microchemistry of samples were studied by transmission electron micropscopy. Perovskite, tungsten–bronze and fresnoite phases developed during crystallization have a strong effect on the resulted dielectric properties with permittivities ranging from 20 to 700. Resistivity measurements were done to study conduction mechanisms in samples and the resistivity values for glass–ceramics were found to be between 1011 and 1013Ω·cm at 150°C. MnO2 additions were made to improve the electrical resistivity of glass–ceramics.