Controllable modulation of patterned vertical graphene through macro-geometries for high current field emitters

In this work, in-situ growth of vertical graphene (VG) in controllable patterns was achieved through macro-geometric modulation of nickel substrates, followed by the adjustment of growth density and size of VG. When VG was grown in controllable patterns, the turn-on electric field decreased from 1.04 V/& mu;m for initial VG to 0.69 V/& mu;m and the current variation of patterned vertical graphene (PVG, 7%) was obviously lower than that of initial VG (23%). The outstanding field emission properties of PVG were essentially attributable to the weakening of field shielding. The COMSOL simulation demonstrated that PVG reduced field shielding and VG grown on Ni aggregation provided stronger contribution to field emission. In addition, structural stability of VG and connection between VG and substrate were observed in SEM and TEM. The results had implications in understanding the influence of structural stability on field emission properties by observing the cross section of VG-substrate and the nano-structure evolution of VG before and after field emission.

Automated summary

In this work, vertical graphene was grown in controllable patterns through macro-geometric modulation of nickel substrates, leading to a decrease in the turn-on electric field and reduced current variation. The outstanding field emission properties of patterned vertical graphene (PVG) were attributed to the weakening of field shielding and stronger contribution from VG grown on Ni aggregation. SEM and TEM observations confirmed the structural stability of VG and its connection to the substrate. The results provide insights into the influence of structural stability on field emission properties.