Facile synthesis of differently shaped, ultrathin, and aligned graphene flakes without a catalyst for highly efficient field emission

- Ultrathin AGFs are prepared without a catalyst by using rf sputtering deposition.
- AGF shapes can be readily controlled by adjusting experimental parameters.
- AGF growth is found to be dependent on substrate geometry and surface topography.
- Optimal field emission performance is obtained from AGF-SiNW composites.