The dielectric properties of atomic layer deposited pure Al2O3 and Si doped Al2O3 thin films were characterized by various measurement techniques. By the use of capacitance voltage and conductance measurements charged defects within the oxide and at the silicon interface were detected. It was shown that the passivation quality of Al2O3 is strongly related to the density of fixed oxide charges Qf and the interface trap density Dit. The fixed charge density could be adjusted from -6.2∙1012 cm-2 for samples annealed at 500°C to +2.1∙1012 cm-2 for as deposited Si doped layers. Additionally current voltage characteristics were performed in a temperature range from 25°C to 125°C. The leakage current was found to increase with higher temperature. A barrier height of 0.4 eV was extracted from the data by assuming a Pool-Frenkel mechanism.

Charge retention measurements on MONOS (metaloxide-nitride-oxide-silicon) capacitor structures were performed in an extended temperature range from 100 to 400 K. Both, thermal excitation (TE) and direct trap to band tunneling (TB) were taken into account to identify the energy distribution of relevant deep level centers. To separate the contribution from TE and TB, a new computation routine based on established approaches was applied. Because of the enlarged temperature range in experiment a corresponding enhanced range of trap energies can be studied. The numerical simulation results in self-consistent energy distributions of the detected trap states.