Light-Emitting Porous Silicon from Cast Metallurgical-Grade Silicon

Strong visible light emissions from porous silicon (PS) prepared from cast metallurgical-grade silicon (MG-Si) are reported for the first time. The Si substrates used for the preparation of the PS films were obtained by directional solidification casting of MG-Si, followed by wafer sawing and lapping. A chemical etching method was used instead of the conventional electrochemical method ofproducing PS. The photoluminescence spectra are characterized by a full width at half maximum of 340 to 370 meV, a 2.0 eV peak energy, and a strong peak intensity.