An ordered Si nanowire with NiSi2 tip arrays as excellent field emitters

Abstract

A method was developed to grow ordered silicon nanowire withNiSi2 tip arrays by reacting nickel thin films on silica-coated ordered Si nanowire (NW) arrays.The coating of thin silica shell on Si NW arrays has the effect of limiting thediffusion of nickel during the silicidation process to achieve the single crystallineNiSi2 NWs.In the meantime, it relieves the distortion of the NWs caused by the strain associated with formation ofNiSi2 tomaintain the straightness of the nanowire and the ordering of the arrays. Other nickel silicide phases suchas Ni2Si and NiSi were obtained if the silicidation processes were conducted on the ordered SiNWs without a thin silica shell. Excellent field emission properties were found forNiSi2/Si NW arrays with a turnon field of 0.82 V µm − 1 and athreshold field of 1.39 V µm − 1. The field enhancement factor was calculated to be about 2440. Thestability test showed a fluctuation of about 7% with an applied field of 2.6 V µm − 1 for a period of 24 h. The excellent field emission characteristics are attributedto the well-aligned and highly ordered arrangement of the single crystallineNiSi2/Si heterostructure field emitters. In contrast to other growth methods, the present growth ofordered nickel silicide/Si NWs on silicon is compatible with silicon nanoelectronics deviceprocesses, and also provides a facile route to grow other well-aligned metal silicide NWarrays. The advantages will facilitate its applications as field emission devices.