Fabrication of Silicon Nanowires with Precise Diameter Control Using Metal Nanodot Arrays as a Hard Mask Blocking Material in Chemical Etching

We report on a simple and cost-effective method to fabricate high density silicon nanowires (SiNWs) through catalytic chemical wet etching. Metallic chromium/gold (Cr/Au) nanodots were first deposited onto the silicon wafer using an anodic aluminum oxide (AAO) template. The AAO template was then removed before a thin blanket layer of gold catalyst was evaporated onto the sample surface. The gold-assisted chemical wet etching was carried out in a solution consisting of deionized water, hydrogen peroxide, and hydrofluoric acid to produce well-aligned silicon nanowires of uniform diameters. We demonstrate that the diameter of the silicon nanowires can be precisely controlled to a precision of 10 nm in the range of 40 to 80 nm through fine-tuning of the pore diameter of the AAO template. The reported fabrication procedure therefore gives a highly repeatable method to form well-aligned, uniform, and crystalline SiNWs of high density with controllable diameters below 100 nm. The use of Cr/Au as a hard mask blocking material will also be of great interest for the fabrication of other Si nanostructures using the catalytic etching process.