Visible Light Emission from Porous Silicon Prepared by Photoetching in Alkaline Solution

We demonstrate that spa water (Tenkeisen Spa water; TeSW) can be used as a solution for preparing porous silicon (PSi). The TeSW is a colorless alkaline solution. Photoetching is carried out on an n-type Si(111) wafer in TeSW under 5 mW He-Ne laser illumination. Photoluminescence from PSi shows a peak at at room temperature. The structural and optical properties of the TeSW-prepared PSi sample are nearly the same as those prepared in HF solution, although neither nor is present in the spa water. This is the first report of preparing light-emitting PSi using alkaline solution.