Modeling Multilayer Thin Barrier Degradation under Coupled Thermo-Electric Stresses
Multilayer barrier longevity requires modeling field-assisted oxygen vacancy drift alongside thermal kinetics to prevent localized dielectric breakdown.
Space Charge Accumulation
Meaning
Concentration of immobile electrical charges within the volume of a dielectric material under a continuous electric field generates severe distortions in the internal electric field distribution. This space charge accumulation is a primary cause of reliability degradation in high-voltage direct-current insulation systems. The process leads to localized stress points that exceed the material design limits, and the charge remains trapped until thermal or electrical release occurs, destabilizing the high-voltage transmission lines.
Drift Mechanism
Applied voltage drives the injection of charge carriers from the electrodes into the insulating layer, where they become trapped at molecular defect sites. These traps consist of chemical impurities, interfaces, or amorphous regions in the polymer structure. The rate of injection depends on the temperature and the electric field strength.
Insulation Breakdown
High fields near the trapped charges can become several times stronger than the average applied field. This concentration of field intensity initiates localized electrical discharges that destroy the chemical bonds of the polymer. The degradation continues until the entire insulation layer is breached.
Material Strategy
Manufacturing processes incorporate nanostructured additives into the polymer to create high densities of shallow traps that encourage charge dissipation. This approach prevents the formation of large localized fields by distributing the charges more uniformly. The modified material maintains high dielectric strength under stress.