Direct graphene growth on transitional metal with solid carbon source and its converting into graphene/transitional metal oxide heterostructure

The oxide/semiconductor structure is key to controlling current in electronic devices and HfO2 is a common gate material in conventional electronic devices due to its favorable dielectric properties. Graphene devices also require insulating gates. We demonstrate a unique direct growth approach to obtain the bottom gate structure (graphene/HfO2/n-SiC). The present approach involves transfer of graphene grown by chemical vapor deposition (CVD) on Cu to oxidized Si wafers, a complex process prone to low yield and reduced performance. Furthermore, HfO2 is preferred to SiO2 because of its superior properties. The proposed concept consists of the direct deposition of graphene by solid carbon molecular beam epitaxy on Hf metal coated n-type SiC, followed by oxygen intercalation to form HfO2. The oxygen intercalation will then convert the underlying Hf into HfO2 due to the strong affinity of Hf with oxygen. We identify the graphene/HfO2 formation by Raman, X-ray photoelectron spectroscopy (XPS), Low energy electron diffraction (LEED), Low energy electron microscopy (LEEM) and electrical properties including Hall mobility and leakage current measurement.

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