First-principles study on energetics of intrinsic point defects in LaAlO₃

Abstract

Using density-functional theory (DFT) calculations, the formation energies, electron affinities and electronic levels of various intrinsic defects in bulk LaAlO₃ are investigated. Results give the atomic structures of charged interstitials, vacancies, Frenkel pairs, antisite defects, and Schottky defects, respectively. It is found that the formation energies of O vacancy are the lowest in the reducing conditions. In contrast, the La vacancy V[sub La] is more favorable in formation energy as the O chemical potential increasing. Moreover, by considering the defect levels of LaAlO₃ with respect to the silicon conduction bands, the effects of the electron and hole trapping in real devices are also simulated. Our results show that the paired charged V[sub O], which lies in the middle of the silicon band gap, should be the key problematic defect. The deep defect level of V[sub O] can induce a large-tunneling-leakage current and cause instability in the device performance. These predictions provide rich defect structures in LaAlO₃ and useful information for the microelectronic designs.