Fig. 2: Atomic-resolution analysis of TiO2/VO2/TiO2 heterostructure. | Nature Communications

Fig. 2: Atomic-resolution analysis of TiO2/VO2/TiO2 heterostructure.

From: Directional ionic transport across the oxide interface enables low-temperature epitaxy of rutile TiO2

Fig. 2

a ABF-STEM, b HAADF-STEM and c LAADF-STEM images of rutile TiO2 epitaxial film grown on VO2 sacrificial template at TG = 150 °C with [100] zone axis (scale bar = 5 nm). The sensitivity of ABF technique to light-weight atoms enables observation of oxygen atoms along the [100] zone axis. Note that the regular pattern from TiO2 epitaxial films (top red square in a) was identical to that from TiO2 substrates (bottom red square in a), indicating an identical atomic arrangement of films with single crystals by epitaxial growth without oxygen defects. On the contrary, the oxygen-deficient region was observed in the sacrificed VO2 template near the TiO2 film (blue square in a). While almost-uniform HAADF contrast was observed across the heterostructures due to similar cation atomic weight across the heterostructures (b), a noticeable strain-field-induced LAADF contrast was observed in VO2 templates (c) sandwiched between TiO2 films and substrates. Yellow lines in b and c are the contrast-intensity profiles of the HAADF and LAADF images from the white rectangular areas.

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