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

Abstract

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/μm for initial VG to 0.69 V/μm 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.