Tunable field emission properties of well-aligned silicon nanowires with controlled aspect ratio and proximity

The size of silicon nanowires (SiNWs) is crucial for their future application in the assembly of field emission (FE) devices. Ag-assisted chemical etching combined with PS sphere as template was employed to prepare size-controllable single crystal SiNWs with uniformity, and the diameter could be further reduced via dry oxidation. The FE properties were found to be strongly influenced by dimensionality and surface geometry structures, and improved progressively with the increase of proximity. The best FE properties were observed in the SiNWs with a tip size of ∼180 nm (period 1000 nm) and a length of 3.2 μm. They showed a low turn-on field of 1.8 V μm −1 and a high current density of 0.75 mA cm −2 at an electric field of 2.5 V μm −1 . The emission current as a function of time test also demonstrated the good robustness of the SiNWs. The enhanced field emitting efficiency is attributed to the large space between neighboring nanowires, enhanced surface roughness and the sharp tips as hot emission spots.