Layer-Resolved Cation Diffusion and Stoichiometry at the LaAlO3/SrTiO3 Heterointerface Probed by X-ray Photoemission Experiments and Site Occupancy Modeling

Giovanni Drera, Luigi Ermenegildo Sangaletti, Gabriele Salvinelli, Alessio Giampietri

Risultato della ricerca: Contributo in rivistaArticolo in rivistapeer review

13 Citazioni (Scopus)

Abstract

The layer-resolved cation occupancy for different conducting and insulating interfaces of LaAlO3 (LAO) thin films on SrTiO3 (STO) has been determined by angle-resoled X-ray photoelectron spectroscopy (AR-XPS). Three STO interfaces with LAO have been considered, namely, a conducting interface with a 5 unit cell (u.c.) LAO layer, an insulating interface with a 5 u.c. LAO layer, and an insulating interface with a 3 u.c. LAO layer. Considering inelastic and elastic scattering processes in the transport approximation, the core-level signal attenuation has been modeled on the basis of Monte Carlo calculations of the electron trajectories across the heterostructures. Different effects involving cation stoichiometry and diffusion through the interface have been considered to interpret data. Beyond a mere abrupt interface modeling, the LaAlO3/SrTiO3 heterojunction is shown to host cation diffusion processes within 3-4 unit cells in the bulk layer, along with a clear Sr substoichiometry, an issue so far virtually neglected in the analysis of these systems. The present results show the capability of the AR-XPS modeling to explore element-sensitive properties at the oxide interfaces, matching and completing the information that can be provided by probes based on electron microscopy or X-ray scattering.
Lingua originaleEnglish
pagine (da-a)25648-25657
Numero di pagine10
RivistaACS APPLIED MATERIALS & INTERFACES
Volume7
DOI
Stato di pubblicazionePubblicato - 2015

Keywords

  • LaAlO3
  • Materials Science (all)
  • SrTiO3
  • cation interdiffusion
  • heterointerfaces
  • intermixing
  • oxides
  • photoemission

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