Fabrication of vertically well-aligned NiSi₂ nanoneedle arrays with enhanced field emission properties

In this study, we demonstrated the controllable fabrication of periodic arrays of vertically well-aligned, fully-silicided NiSi₂ nanoneedles with sharp nanotips on (100)Si substrates. The new approach proposed here eliminates the need for complicated and costly photolithographic processes and the use of toxic chemicals. All the produced vertical Si and NiSi₂ nanoneedles were identified to be single crystalline and with the same geometric morphology and the same axial orientation of [100]. Additionally, the produced tapered NiSi₂ nanoneedle array possessed excellent electron emission properties with a very low turn-on field of 0.85 V/μm, which is superior to many reported one-dimensional metal silicide nanostructures. Such an enhancement in the field emission can be attributed to the lower effective work function, sharp nanotips, single-crystalline structure, and good vertical alignment. The combination of the facile approach proposed here and superior electron emission performances make the well-ordered vertical NiSi₂ nanoneedles promising candidates for vacuum nanoelectronics and field emission display applications.