Graphene films by chemical vapor deposition (CVD) draw much attention for the future applications with their extraordinary properties1,2. However, wrinkles formed by the strong coupling to the growing substrates inevitably emerge and limit the large-scale homogeneity3,4. Here, we develop CVD method to grow ultra-flat graphene films with wrinkle-free and quasi-suspending features5. The formed wrinkles by traditional CVD can also be reduced by these processes, and some of them even disappear due to the decoupled van der Waals interactions and the probably increased surface distance. The ultra-flat graphene films show V-shape Dirac cone and linear dispersion at the atomic plane or across the atomic step, confirming their homogenous decoupling. The ultra-flatness of the graphene films ensures their surfaces easy-clean after wet transfer process, and a robust quantum Hall effect even appears in a device of 100 μm linewidth at room temperature. These CVD grown graphene films should retain their intrinsic extraordinary performances to large extent. 

References

[1] Bae, S. K. et al. Roll-to-roll production of 30-inch graphene films for transparent electrodes. Nat. Nanotech. 5, 574-578 (2010).

[2] Lee, J. H. et al. Wafer-Scale Growth of Single-Crystal Monolayer Graphene on Reusable Hydrogen-Terminated Germanium. Science 344, 286-289 (2014).

[3] Zhu, W. et al. Structure and electronic transport in graphene wrinkles. Nano Lett. 12, 3431-3436 (2012).

[4] Bronsgeest, M. S. et al. Strain Relaxation in CVD Graphene: Wrinkling with Shear Lag. Nano Lett. 15, 5098-5104 (2015).

[5] Yuan, G. W. et al. Proton Assisted Growth of Ultra-flat Graphene Films. Nature 577, 204–208 (2020).

Graphene films by chemical vapor deposition (CVD) draw much attention for the future applications with their extraordinary properties1,2. However, wrinkles formed by the strong coupling to the growing substrates inevitably emerge and limit the large-scale homogeneity3,4. Here, we develop CVD method to grow ultra-flat graphene films with wrinkle-free and quasi-suspending features5. The formed wrinkles by traditional CVD can also be reduced by these processes, and some of them even disappear due to the decoupled van der Waals interactions and the probably increased surface distance. The ultra-flat graphene films show V-shape Dirac cone and linear dispersion at the atomic plane or across the atomic step, confirming their homogenous decoupling. The ultra-flatness of the graphene films ensures their surfaces easy-clean after wet transfer process, and a robust quantum Hall effect even appears in a device of 100 μm linewidth at room temperature. These CVD grown graphene films should retain their intrinsic extraordinary performances to large extent. 

References

[1] Bae, S. K. et al. Roll-to-roll production of 30-inch graphene films for transparent electrodes. Nat. Nanotech. 5, 574-578 (2010).

[2] Lee, J. H. et al. Wafer-Scale Growth of Single-Crystal Monolayer Graphene on Reusable Hydrogen-Terminated Germanium. Science 344, 286-289 (2014).

[3] Zhu, W. et al. Structure and electronic transport in graphene wrinkles. Nano Lett. 12, 3431-3436 (2012).

[4] Bronsgeest, M. S. et al. Strain Relaxation in CVD Graphene: Wrinkling with Shear Lag. Nano Lett. 15, 5098-5104 (2015).

[5] Yuan, G. W. et al. Proton Assisted Growth of Ultra-flat Graphene Films. Nature 577, 204–208 (2020).