Papers by Keyword: Conduction Mechanisms

Abstract: The increased demand for SiC power MOSFETs requires gate dielectrics with low defect densities and high reliability under high electric field and temperature conditions. In this work, we examine how oxidant chemistry and deposition temperature affect the electrical properties of Al₂O₃/SiO₂ bilayer dielectrics formed in n-type 4H-SiC MOS capacitors. These structures consist of a thin SiO₂ interfacial layer, over which Al₂O₃ is deposited via ALD using three different oxidants at a temperature of 150–350°C. C–V and temperature-dependent I–V (25–150°C) measurements show that the choice of oxidant influences the flat band voltage shift and leakage current density, with a process-dependent trade-off between optimizing each parameter. These findings highlight that precise control of oxidant chemistry during ALD is essential for balancing flat band voltage stability with leakage suppression, and that multilayer-specific conduction models are critical for accurately predicting high electric field leakage characteristics in advanced SiC gate stacks.

Abstract: The conduction characteristics of Polyaniline emeraldine salt-Graphite (PAni-ES/Gr) pellets were characterized using an impedance analyzer. The pellets were prepared with varying mass fractions of PAni-ES and Gr. FTIR spectra have the stretching vibrations for PAni-ES and absence of peaks for Gr. PAni-ES showed aggregated particles while Gr appeared as sheets and flaky structures. The composition of the pellets was differentiated in the AC conductivity values. The critical frequency representing the transition from frequency-independent to frequency-dependent conductivity decreases with increasing Gr content. Lastly, the frequency-dependent conductivity behavior follows power-law behavior reflecting possible hopping mechanisms and random resistor-capacitor network.

Abstract: The transient conductivity in low-density polyethylene is studied. Isochronal currentvoltage measurements for 1800 s and 1 day time intervals are carried out under dry N2 atmosphere. When after every measurement the sample is fully discharged at high temperature the isochronal current - voltage characteristic reveals an ohmic behavior. When the next field increase is applied without sample discharging the current-voltage characteristic is super-quadratic. We explain this increase of the current assuming that a fraction of the previous injected charge is detrapped by the field and it contributes to current increase. Consequently the current – voltage characteristic is strongly dependent on the time lag between two successive rises in the field. Neither the Poole-Frenkel mechanism nor the Richardson – Schottky mechanism can by used to explain the experimental results. The isothermal charging and discharging currents are explained assuming the movement of injected/ejected charge in the resultant local field. The values obtained for the adjustable parameters of the model are in good agreement with the values in the literature.