Preparation of multi-layer graphene on nickel-coated silicon microchannel plates by a hydrothermal carbonization procedure and its improved field emission properties

An emission cell comprising multi-layer graphene (MLG) on nickel-coated silicon microchannel plates (Ni/Si-MCPs) was prepared. The Ni₃C film was formed on the Si-MCPs by hydrothermal carburization in a polyol solution containing a small amount of NaAc as the carbon source and thermal annealing was performed to produce the vertically and horizontally aligned multi-layer graphene field-emission cathode on the surface of the Ni/Si-MCPs (MLG-MCPs). The microstructure and surface morphology were investigated and field emission (FE) studies indicated that the MLG-MCPs delivered better FE performance than Ni/Si-MCPs due to characteristics such as sharp edges, large aspect ratio, and the vertically and horizontally aligned and patterned MLG with good electrical conductivity. The turn-on field of the sample annealed at 800 °C was 2.0 V μm^-1 at a current density of 10 μA cm^-2 and the field emission threshold was 3.2 V μm^-1 at 1 mA cm^-2. The structure was very stable showing 97.5% retention after continuous operation for over 6 h at 2 × 10^-5 Pa, suggesting a promising candidate for FE devices. This would open up possibilities for the next generation FE electron sources from well-aligned macroporous graphene with skeleton and extend their practical applications.