Interface energetics and atomic structure of epitaxial La{sub 1−x}Sr{sub x}CoO{sub 3} on Nb:SrTiO{sub 3}

• Published in: Applied physics letters 2015-06, Vol.106 (24)
• Main Authors: Van Overmeere, Quentin, Baniecki, John D., Yamazaki, Takashi, Aso, Hiroyuki, Kataoka, Yuji, Imanaka, Yoshihiko, Ricinschi, Dan, Miyata, Yusuke, Yamada, Hiroaki, Fujimura, Norifumi
• Format: Article
• Language: English
• Subjects: CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; DENSITY FUNCTIONAL METHOD; DOPED MATERIALS; ENERGY-LOSS SPECTROSCOPY; EPITAXY; INTERFACES; OXIDES; PHOTOELECTRON SPECTROSCOPY; SEMICONDUCTOR MATERIALS; SENSITIVITY; STRONTIUM TITANATES; THIN FILMS; TRANSMISSION ELECTRON MICROSCOPY; VACANCIES; X RADIATION
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4922880

The energetics at oxide semiconductor/La{sub 1−x}Sr{sub x}CoO{sub 3} heterojunctions, including the respective alignment of the valence and conduction bands, govern charge transfer and have to be determined for the design of future La{sub 1−x}Sr{sub x}CoO{sub 3}-based devices. In this letter, the electronic and atomic structures of epitaxial La{sub 1−x}Sr{sub x}CoO{sub 3} on Nb-doped strontium titanate are revealed by scanning transmission electron microscopy, electron energy loss spectroscopy, and in situ x-ray and ultra violet photoelectron spectroscopies. For LaCoO{sub 3}, a valence band (VB) offset of 2.8 ± 0.1 eV is deduced. The large offset is attributed to the orbital contributions of the Co 3d states to the VB maximum of the LaCoO{sub 3} thin films, with no evidence of interface dipole contributions. The sensitivity of the valence band orbital character to spin state ordering and oxygen vacancies is assessed using density functional theory.