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Successful application of spatial difference technique to electron energy‐loss spectroscopy studies of Mo/SrTiO 3 interfaces
Author(s) -
Gao M.,
Scheu C.,
Tchernychova E.,
Rühle M.
Publication year - 2003
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1046/j.1365-2818.2003.01174.x
Subject(s) - electron energy loss spectroscopy , spectroscopy , transmission electron microscopy , k edge , materials science , substrate (aquarium) , electron , high resolution transmission electron microscopy , analytical chemistry (journal) , scanning transmission electron microscopy , thin film , atomic physics , absorption spectroscopy , chemistry , molecular physics , crystallography , optics , nanotechnology , physics , oceanography , chromatography , quantum mechanics , geology
Summary The electron energy‐loss near‐edge structure (ELNES) of Mo/SrTiO 3 interfaces has been studied using high spatial resolution electron energy‐loss spectroscopy (EELS) in a dedicated scanning transmission electron microscope. Thin films of Mo with a thickness of 50 nm were grown on (001)‐orientated SrTiO 3 surfaces by molecular beam epitaxy at 600 °C. High‐resolution transmission electron microscopy revealed that the interfaces were atomically abrupt with the (110) Mo plane parallel to the substrate surface. Ti‐L 2,3 (∼460 eV), O‐K (∼530 eV), Sr‐L 2,3 (∼1950 eV) and Mo‐L 2,3 (∼2500 eV) absorption edges were acquired by using the Gatan Enfina parallel EELS system with a CCD detector. The interface‐specific components of the ELNES were extracted by employing the spatial difference method. The interfacial Ti‐L 2,3 edge shifted to lower energy values and the splitting due to crystal field became less pronounced compared to bulk SrTiO 3 , which indicated that the Ti atoms at the interface were in a reduced oxidation state and that the symmetry of the TiO 6 octahedra was disturbed. No interfacial Sr‐L 2,3 edge was observed, which may demonstrate that Sr atoms do not participate in the interfacial bonding. An evident interface‐specific O‐K edge was found, which differs from that of the bulk in both position (0.8 ± 0.2 eV positive shift) and shape. In addition, a positive shift (0.9 ± 0.3 eV) occurred for the interfacial Mo‐L 2,3 , revealing an oxidized state of Mo at the interface. Our results indicated that at the interface SrTiO 3 was terminated with TiO 2 . The validity of the spatial difference technique is discussed and examined by introducing subchannel drift intentionally.