High-quality VO \(_2\) films were fabricated on top of c-Al \(_2\) O \(_3\) substrates using Reactive Bias Target Ion Beam Deposition (RBTIBD) and the studies of graphene/VO \(_2\) heterostructure were conducted. Graphene layers were placed on top of \(\sim\) 50 and \(\sim\) 100 nm VO \(_2\) . The graphene layers were introduced using mechanical exfoliate and CVD graphene wet-transfer method to prevent the worsening crystallinity of VO \(_2\) , to avoid the strain effect from lattice mismatch and to study how VO \(_2\) can affect the graphene layer. Slight increases in graphene/VO \(_2\) T \(_\text {MIT}\) compared to pure VO \(_2\) by \(\sim\) 1.9 \(^{\circ }\) C and \(\sim\) 3.8 \(^{\circ }\) C for CVD graphene on 100 and 50 nm VO \(_2\) , respectively, were observed in temperature-dependent resistivity measurements. As the strain effect from lattice mismatch was minimized in our samples, the increase in T \(_\text {MIT}\) may originate from a large difference in the thermal conductivity between graphene and VO \(_2\) . Temperature-dependent Raman spectroscopy measurements were also performed on all samples, and the G-peak splitting into two peaks, G \(^{+}\) and G \(^{-}\) , were observed on graphene/VO \(_2\) (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 \(_2\) phase transition mechanism. The 2D-peak measurements also show large blue-shifts around 13 cm \(^{-1}\) at room temperature and slightly red-shifts trend as temperature increases for 100 nm VO \(_2\) samples. Other electronic interactions between graphene and VO \(_2\) are expected as evidenced by 2D-peak characteristic observed in Raman measurements. These findings may provide a better understanding of graphene/VO \(_2\) and introduce some new applications that utilize the controllable structural properties of graphene via the VO \(_2\) phase transition.
