Porous silicon formation by photoetching in HF/H2O2 solution using incoherent light source

An approach to forming porous silicon (PSi) formation has been developed using a photoetching method with HF/H2O2 solution under Xe lamp illumination. The sulphuric peroxide mixture (SPM) cleaning of a n-Si substrate makes possible the stable formation of PSi layer on the front surface. Yellow photoluminescence is observed, which is about 40 times stronger than that without SPM cleaning. The addition of H2O2 to HF solution results in the formation of a PSi layer in a short time. The surface topography as characterized by atomic force microscopy reveals features on the order of 10-100nm. The photoetching mechanism can be explained with the aid of a surface energy-band diagram of n-Si in the HF/H2O2 electrolyte.