Structures and field emission properties of silicon nanowires irradiated with energetic carbon ion beam

In this paper, the structures and field emission properties of energetic C ion irradiated SiNWs have been investigated and influence of ion irradiation on structures and properties has been discussed. Vertically SiNW arrays are synthesized by using Ag-assisted electroless-chemical etching at room temperature, as reported in literatures. The process mainly comprises three steps: 1) surface cleaning of polished silicon wafers; 2) immersion of the cleaned silicon wafers into HF-based aqueous solution containing silver nitrate to synthesize Ag catalyst; 3) chemical etching of the Ag catalyst-covered silicon wafers in HF-base aqueous solution containing oxidant (H₂O₂). After throughout above processes, SiNW arrays have been synthesized. Then, the samples are immersed in 50% HNO₃ solution to dissolve Ag catalyst. The as-grown SiNWs are irradiated by energetic carbon ion with an average energy of 20 keV and various doses. FE-SEM, EDS and XPS are employed to characterize the morphology and chemical structures of samples. The field emission measurement is carried out in an ultrahigh vacuum chamber with a bi-diode system, in which the base pressure is lower than 3x10^-7 Pa.