Heterogeneous integration of single-crystalline rutile nanomembranes with steep phase transition on silicon substrates.

Lee, Dong Kyu; Park, Yunkyu; Sim, Hyeji; Park, Jinheon; Kim, Younghak; Kim, Gi-Yeop; Eom, Chang-Beom; Choi, Si-Young et al. · Nat Commun · 2021

basic_science · Level V

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Abstract

Unrestricted integration of single-crystal oxide films on arbitrary substrates has been of great interest to exploit emerging phenomena from transition metal oxides for practical applications. Here, we demonstrate the release and transfer of a freestanding single-crystalline rutile oxide nanomembranes to serve as an epitaxial template for heterogeneous integration of correlated oxides on dissimilar substrates. By selective oxidation and dissolution of sacrificial VO<sub>2</sub> buffer layers from TiO<sub>2</sub>/VO<sub>2</sub>/TiO<sub>2</sub> by H<sub>2</sub>O<sub>2</sub>, millimeter-size TiO<sub>2</sub> single-crystalline layers are integrated on silicon without any deterioration. After subsequent VO<sub>2</sub> epitaxial growth on the transferred TiO<sub>2</sub> nanomembranes, we create artificial single-crystalline oxide/Si heterostructures with excellent sharpness of metal-insulator transition ([Formula: see text] > 10<sup>3</sup>) even in ultrathin (<10 nm) VO<sub>2</sub> films that are not achievable via direct growth on Si. This discovery offers a synthetic strategy to release the new single-crystalline oxide nanomembranes and an integration scheme to exploit emergent functionality from epitaxial oxide heterostructures in mature silicon devices.