Direct growth of graphene on transition metal oxides via atmospheric pressure chemical vapor deposition

The graphene/transition metal oxides (TMOs) hybrid heterostructures have exhibited the synergetic behaviors, which could not be anticipated in single materials owing to the formation of heterointerface. [1, 2, 3, 4] Typically, the fabrication of hybrid heterostructure predominantly depended on the transfer process of graphene, conventionally grown via chemical vapor deposition (CVD) on metal catalysts, such as Cu, Ni, and Pt with a higher carbon solubility. [5] Consequently, these hybrid heterostructures could not maintain a consistent quality, originated from the typical transfer procedure, including electron doping [6] and mechanical and chemical damage to graphene. [7] The direct growth of graphene onto TMO substrates can avoid these issues, ensuring superior quality and uniformity in the hybrid heterostructures, even within a narrow growth window.

In this study, we directly synthesized graphene on SrTiO₃ (001) substrates at 1100°C, utilizing Ar, H₂, and CH₄ as precursors via atmospheric pressure CVD (APCVD) method. We successfully fabricated full coverage (5x5 mm²) of high-quality graphene on SrTiO₃ substrates with preserving the SrTiO₃ step-terrace structure, confirmed by Raman spectroscopy, atomic force microscopy, and scanning electron microscopy. We found that full coverage of graphene on SrTiO₃ via APCVD necessitates a sufficient deposition temperature and CH₄ flow. Furthermore, we observed that the reduction of the H₂ flow rate improves graphene quality with less residues at the surface. We also conducted the direct fabrication of graphene on other TMO substrates, especially LaAlO₃ and (LaAlO₃)_0.3(SrAl_0.5Ta_0.5O₃)_0.7. Our research offers to standardize the fabrication method for enabling the production of high-quality graphene/TMO hybrid heterostructures using APCVD.





[1] Kang et al., Adv. Mater, 34, 1803732 (2019).

[2] Park et al., Nano Lett, 3, 1754-1759 (2016).

[3] Kang et al., Adv. Mater, 18, 1700071 (2017).

[4] Shin et al., Adv. Funct. Mater, Early Veiw, 2311287 (2023).

[5] Munoz et al., Chem. Vap. Deposition, 19, 297-322 (2013).

[6] Wu et al., RSC Adv, 9, 41447-41452 (2019).

[7] Yoon et al., Sensors. 10, 3944 (2022).