Stoichiometry Dependence of Potential Screening at La${}_{(1-\delta )}$Al${}_{(1+\delta )}$O${}_3$/SrTiO${}_3$ Interfaces

Abstract

Hard x-ray photoelectron spectroscopy (HAXPES) and variable kinetic energy x-ray photoelectron spectroscopy (VKE-XPS) analyses have been performed on 10 unit cell La${}_{(1-\delta )}$Al${}_{(1+\delta )}$O${}_3$ films, with La:Al ratios of 1.1, 1.0, and 0.9, deposited on SrTiO${}_3$. Of the three films, only the Al-rich film was known to have a conductive interface. VKE-XPS, coupled with maximum entropy analysis, shows significant differences in the compositional depth profile between the Al-rich, the La-rich, and stoichiometric films; significant La enrichment at the interface is observed in the La-rich and stoichiometric films, while the Al-rich shows little to no intermixing. Additionally, the La-rich and stoichiometric films show a high concentration of Al at the surface, which is not observed in the Al-rich film. HAXPES valence band (VB) analysis shows a broadening of the VB for the Al-rich sample relative to the stoichiometric and La-rich samples, which have insulating interfaces. This broadening is consistent with an electric field across the Al-rich film. These results are consistent with a defect driven electronic reconstruction.

arXiv comment8 pages, 9 figures

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Cited by in corpus (5)

• Interface chemical and electronic properties of LaAlO3/SrVO3 heterostructures
• Band offsets at amorphous-crystalline $A{l}_2{O}_3-SrTi{O}_3$ oxide interfaces
• Hopping Transport in SrTiO3/Nd1-xTiO3/SrTiO3 Heterostructures
• The impact of the near-surface region on the interpretation of x-ray absorption spectroscopy
• Formation of a conducting LaAlO${}_3$ / SrTiO${}_3$ interface studied by low energy electron reflection during growth