Defect states in the high-dielectric-constant gate oxide LaAlO3

Abstract

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Electronic structure of oxygen vacancies inSrTiO3andLaAlO3

“…HSE further opens up the band gap placing the V 0 level at 2.19 eV below the conduction band edge (it is 1.32 eV in the LDA). Our results differ from that reported in [40] where the defect state is found to be less deep. Discrepancies could arise due to the different supercell size used.…”

“…Discrepancies could arise due to the different supercell size used. Further, the band gap obtained with screened exchange in [40] Since the neutral oxygen vacancy defect in LAO is a deep defect we further check the presence of V -and V --state inside the gap. We do not find any states occurring within the band gap of LAO corresponding to the above charged states.…”

Ab initiodefect energetics of perovskite (001) surfaces for solid oxide fuel cells: A comparative study ofLaMnO3versusSrTiO3andLee1, Morgan2 2015Phys. Rev. B433360View full textAdd to dashboardCite

“…4(b). While the energy of Vö formation in mixed ionic-electronic conductors can often be described by two electrons going from the O 2p band center to E Fermi [6], the energy levels of the Vö defect states localized around the O vacancy in the metallized AO surface are lower in energy than the AO surface states [81]. The energy of the electrons involved in this defect formation is quite similar to the case of the bulk vacancy formation, where two electrons move from the O 2p band to the defect states close to the CBM.…”

“…4(c). Formation of Vö liberates two electrons, and in the bulk system these electrons fill defect states in the gap close to the conduction band minimum (CBM) [81], while in the hole-doped LaAlO 3 symmetric slab these electrons can fill levels near the valence band maximum (VBM), which costs significantly less energy than filling near the CBM. Again, the fact that E seg (Vö) in the center layer of the 15-layer slab does not converge to the bulk (i.e., yield a zero segregation energy) is consistent with the fact that the surface charge screening length is much longer than the thickness of the simulated symmetric slab for LaAlO 3 .…”

First-principles study of polar LaAlO (001) surface stabilization by point defects

“…Several point defects in bulk LAO and O vacancies in LAO (001) film have been studied theoretically [33][34][35][36]. Using density functional theory Zhang et al [35] have recently shown that O vacancy preferably forms at the AlO 2 surface of the LAO overlayer on STO.…”