Photoinduced synthesis of porous silicon without anodization

An easy and very reproducible method to produce porous silicon by light‐stimulated etching of crystalline silicon in HF is described, and the formation mechanism is discussed in terms of carrier diffusion and band bending near the surface. The method avoids the use of electrodes and electrochemical etching. The photosynthesized porous silicon shows bright photoluminescence. Spectra recorded at room temperature for n‐type as well as p‐type silicon are presented.