High-field transient behaviour of thin RF sputtered Al-Al2O3-Al films

Abstract

Charging and discharging current transients have been measured as a function of voltage and film thickness on thin sputtered films of Al₂O₃ in Al-Al₂O₃-Al junctions. These currents decay with time as I varies as exp(-t/ tau ) for short times and t^-n1 for longer times, followed by a t^-n2 dependence. The relaxation time tau primarily increases with voltage and saturates for higher voltages. The coefficient n₁ tends to increase with decreasing voltage, while n₂ increases with voltage. Current theories of I-t response based on space charge and polarization effects do not generally predict the two-stage t^-n dependence. Their physical bases are outlined, and possible modifications to them are briefly discussed.