Metal-insulator transition effect on Graphene/VO[Formula: see text] heterostructure via temperature-dependent Raman...

High-quality VO[Formula: see text] films were fabricated on top of c-Al[Formula: see text]O[Formula: see text] substrates using Reactive Bias Target Ion Beam Deposition (RBTIBD) and the studies of graphene/VO[Formula: see text] heterostructure were conducted. Graphene layers were placed on top of [Formula: see text] 50 and [Formula: see text] 100 nm VO[Formula: see text]. The graphene layers were introduced using mechanical exfoliate and CVD graphene wet-transfer method to prevent the worsening crystallinity of VO[Formula: see text], to avoid the strain effect from lattice mismatch and to study how VO[Formula: see text] can affect the graphene layer. Slight increases in graphene/VO[Formula: see text] T[Formula: see text] compared to pure VO[Formula: see text] by [Formula: see text] 1.9 [Formula: see text]C and [Formula: see text] 3.8 [Formula: see text]C for CVD graphene on 100 and 50 nm VO[Formula: see text], respectively, were observed in temperature-dependent resistivity measurements. As the strain effect from lattice mismatch was minimized in our samples, the increase in T[Formula: see text] may originate from a large difference in the thermal conductivity between graphene and VO[Formula: see text]. Temperature-dependent Raman spectroscopy measurements were also performed on all samples, and the G-peak splitting into two peaks, G[Formula: see text] and G[Formula: see text], were observed on graphene/VO[Formula: see text] (100 nm) samples. The G-peak splitting is a reversible process and may originates from in-plane asymmetric tensile strain applied under the graphene layer due to the VO[Formula: see text] phase transition mechanism. The 2D-peak measurements also show large blue-shifts around 13 cm[Formula: see text] at room temperature and slightly red-shifts trend as temperature increases for 100 nm VO[Formula: see text] samples. Other electronic interactions between graphene and VO[Formula: see text] are expected as evidenced by 2D-peak characteristic observed in Raman measurements. These findings may provide a better understanding of graphene/VO[Formula: see text] and introduce some new applications that utilize the controllable structural properties of graphene via the VO[Formula: see text] phase transition.