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

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 VO₂ buffer layers from TiO₂/VO₂/TiO₂ by H₂O₂, millimeter-size TiO₂ single-crystalline layers are integrated on silicon without any deterioration. After subsequent VO₂ epitaxial growth on the transferred TiO₂ nanomembranes, we create artificial single-crystalline oxide/Si heterostructures with excellent sharpness of metal-insulator transition ([Formula: see text] > 10³) even in ultrathin (<10 nm) VO₂ 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.