The electrical properties of Al2O3 films have been studied as the dielectric materials for electronic devices which require a low leakage current and high breakdown field. In this work, Al2O3 films with various thicknesses (as low as 10-30 nm) were deposited onto Si substrates by plasma-enhanced atomic layer deposition (PEALD), and current density field curves were measured after post-annealing to verify their electrical properties. One thing to note is that, during PEALD, nitrogen gas was introduced to improve the thermal stability of the Al2O3 films. Breakdown field for add-nitrogen Al2O3 of 30 nm-thick film was enhanced from 6 MV/cm to 10 MV/cm as incorporating nitrogen. (C) 2016 Elsevier Ltd. All rights reserved.