Transient currents in thin RF sputtered Al2O3films

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Abstract
Charging and discharging currents have been measured in sandwich structures as a function of applied voltage, temperature and film thickness with both electrodes aluminium or gold. It is suggested that the general shapes of the I-t curves are largely controlled by the contact characteristics, which at a given temperature are blocking below a critical field Ec and injecting above it. For applied voltages U and film thicknesses L, such that U/Lc, there is no injection at time zero, but it may commence at later times if the electrode field rises above Ec due to the drift of a low equilibrium density of free carriers. As the temperature increases, the critical field value decreases and may become insignificant compared with the applied field, leading to injection from time zero.