Nanowires: Decoupling Diameter and Pitch in Silicon Nanowire Arrays Made by Metal-Assisted Chemical Etching (Adv. Funct. Mater. 1/2014)




A combination of metal-assisted chemical etching and nanosphere lithography is used by P. E. Pehrsson and co-workers to make vertically aligned, crystalline silicon nanowire arrays over multiple cm2 areas. On page 106, these relatively smooth nanowires are 55 nm in diameter and are separated from each other by 490 nm. The smoothness and large pitch-to-diameter ratio are achieved through large-scale reduction (∼90%) of the nanospheres by carefully controlled inductively coupled plasma etching, a Ti adhesion layer to enhance the lift-off yield of the catalyst layer, and optimized catalyzed etching parameters.