Electron energy loss spectroscopy determination of Ti oxidation state at the (001) LaAlO3/SrTiO3 interface as a function of LaAlO3 growth conditions

Jean-Luc Maurice (1) , Gervasi Herranz (1) , Christian Colliex (2) , Isabelle Devos (3) , Cécile Carrétéro (1) , Agnès Barthelemy (1) , Karim Bouzehouane (1) , Stéphane Fusil (1) , Dominique Imhoff (2) , Éric Jacquet (1) , François Jomard (4) , Dominique Ballutaud (4) , Mario Basletic (1)

1 Laboratoire Albert Fert (ex-UMPhy Unité mixte de physique CNRS/Thales)
2 LPS - Laboratoire de Physique des Solides
3 IEMN - Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520
4 GEMAC - Groupe d'Etude de la Matière Condensée

At the (001) interface between the two band-insulators LaAlO3 and SrTiO3, a high-mobility electron gas may appear, which has been the object of numerous works over the last four years. Its origin is a subject of debate between the interface polarity and unintended doping. Here we use electron energy loss 'spectrum images', recorded in cross-section in a scanning transmission electron microscope, to analyse the Ti3+ ratio, characteristic of extra electrons. We find an interface concentration of Ti3+ that depends on growth conditions.

Mots clés: Electron energy loss spectroscopy; Electron states at surfaces and interfaces; Electrical properties of specific thin films: insulators

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Jean-Luc Maurice, Gervasi Herranz, Christian Colliex, Isabelle Devos, Cécile Carrétéro, et al.. Electron energy loss spectroscopy determination of Ti oxidation state at the (001) LaAlO3/SrTiO3 interface as a function of LaAlO3 growth conditions. EPL - Europhysics Letters, 2008, 82, pp.17003. ⟨10.1209/0295-5075/82/17003⟩. ⟨hal-00193115⟩