Dependence of substrate orientation and etching conditions on the formation of Si nanowires

Abstract

In this paper, an electroless etching using a mixed solution of hydrofluoric acid and silver nitrite on (100) and (111) silicon substrates was conducted which led to the formation of well-aligned nanowire arrays. In (100) silicon substrate, the density of nanowires networks are much wider apart than that in (111) Si substrate. In addition, the length of the nanowires in (100) Si substrate is almost two times longer than that on (111) Si substrate. It is possibly due to the fact of the orientation where the atoms are much closer packed together in (111), indicating that the process may require more energy to etch deeper and wider. It is also observed the length of SiNWs has increased when the etching temperature increases from 25°C to 50°C. Similar behavior is also noted as the hydrofluoric acid molar concentration increases from 1M to 5 M. © 2011 American Institute of Physics.