Fabrication of porous silicon nanotips by using argon ion-beam irradiation

Porous silicon nanotips (NTs) are promising in many applications such as field emission, superhydrophobicity, solar cells and photoluminescence. Ion irradiation can create unique nanostructures in many types of materials at room temperature, and this paper reports the surface morphology of porous silicon irradiated by an Ar+ ion beam. Different porous silicons are irradiated, and the effects of the ion’s angle of incidence on the porous silicon nanostructure are investigated. High-density NTs of less than 50 nm in size are observed on the porous silicon. The NT size increases, but NT density decreases, with increasing pore size. The orientation of the NTs can be controlled by adjusting the ion impact. Our results reveal that the NTs located at the thick wall between pores and charges created on the tip during Ar+ ion irradiation are beneficial to the formation of the NTs.