Fabrication of silicon field emitter by forming porous silicon

Silicon field emitter array has been fabricated using porous silicon formation in HF solution. Porous silicon layers are formed on n-type silicon wafer with n⁺ layer and p-type silicon wafer in order to make tips. Then, the porous silicon layer is thermally oxidized to be used as an insulator between the gate metal and the silicon substrate. The anode currents of 130 nA per tip and 1 nA per tip are obtained at a gate voltage of 100 V for the n-type emitter and the p-type emitter, respectively. The gate current are less than 0.5% of the anode current for both types.