Controlled growth of vertical graphene nanosheets via plasma flow screening

In this study, the growth of vertical graphene (VG) nanosheets on copper (Cu) substrates in a direct-current plasma-enhanced chemical vapor deposition (PECVD) system was studied. The plasma process during the VG growth was characterized using a high-speed camera and optical emission spectroscopy. Results showed that the plasma composition remained constant, but the overall plasma intensity increased with increasing substrate open area (OA). At low OAs of > 0.05, VG growth was limited to edges, and the VG height increased gradually to reach 700 nm as more reactants became readily available. Two distinctive regimes were identified: diffusion-limited growth at OAs < 0.6, and kinetic-limited growth at OAs > 0.6 for Cu meshes and screens. Under the diffusion-limited regime, VG growth occurred preferentially from the substrate edge toward the center. Therefore, the deposition time was extended to achieve uniform VG deposition. However, in the kinetic-limited regime, the increased availability of reactants did not alter the VG height, which remained at 700 nm. The kinetic-limited deposition was uniform across the substrate due to less plasma screening. This study sheds light on the growth mechanism of VG on perforated substrates, opening new avenues to control deposition on Cu substrates within plasma-screened interfaces.