Strain-induced indirect-to-direct bandgap transition in an np-type LaAlO3/SrTiO3(110) superlattice. Issue 13 (18th March 2019)

• Record Type: Journal Article
• Authors: Wang, L.; Pan, W.; Hu, W. X.; Sun, D. Y.
• Is Part Of: Physical chemistry chemical physics. Volume 21:Issue 13(2019)
• Page Start: 7075
• Page End: 7082
• Publication Date: 2019-03-18
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c8cp07761d
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : By applying uniaxial in-plane strains, an indirect-to-direct bandgap transition occurs in the polar LaAlO3 /SrTiO3 (110) superlattices. Abstract : Using first-principles calculations, we studied the influence of in-plane strain on the electronic properties of the polar LaAlO3 /SrTiO3 (LAO/STO)(110) superlattice. We propose that alternate positively (n-type) and negatively (p-type) charged interfaces can be introduced along the [110] direction, without changing the stoichiometry of the system, if the np-type LAO/STO(001) superlattice is constructed in a 45° stepped pattern. We find that when the LAO–STO layer thickness is larger than the critical thickness of the insulator–metal transition, a quasi-two dimensional hole gas and an anisotropic quasi-two dimensional electron gas are formed at alternate interfaces. By applying uniaxial in-plane strains, an unexpected indirect-to-direct bandgap transition occurs in the polar LAO/STO(110) superlattices. The strain-induced changes in the O-2p orbitals near the p-type interface modify the dispersion of valence-band edges, leading to the transition.