Optimize the field emission character of a vertical few-layer graphene sheet by manipulating the morphology

Vertical few-layer graphene (FLG) sheets have been fabricated by using microwave-plasma-enhanced chemical vapour deposition. Their shape was manipulated through adjusting the growth time and hydrocarbon gas ratio. The growth mechanism during different growth stages is discussed. The field emission characteristics for different FLG shapes were tested and found to be strongly influenced by the tip shape, the height and the amorphous carbon content. The optimal shape of vertical FLG for field emission had fewer layers, sharp corners, large height and was free of amorphous carbon. The best field emission properties with the optimal shape were observed with a turn-on field of 1 : 8 V mu m(-1) and maximum current density of 7 mA cm(-2).