Point defects in Al2O3 and their impact on gate stacks

We consider Al2O3 as a possible gate-stack material, and study defects in the low density kappa-phase. The choice of the kappa-Al2O3 phase is based on the similarity of its density to that of amorphous Al2O3. We analyze native point defects such as vacancies, self-interstitials, and antisites. Our first-principles calculations are based on density functional theory in the local density approximation. Hybrid functionals were utilized as a means of overcoming the band-gap problem. This approach allows us to accurately assess the positions of defect levels. We use calculated band offsets to make predictions about the location of these defect levels with respect to the band edges of relevant semiconductors used as channel materials. We will discuss which defects may impede the optimal performance of devices. (C) 2009 Elsevier B.V. All rights reserved.