Enhanced Near-Edge Transitions by Unsaturated Si Atomsin Porous Silicon

The photo-induced transition probability for porous silicon under different surface conditions is studied. The enhanced near-edge transitions for the presence of unsaturated Si atoms at the surface of porous silicon are found. The theoretical results are in good agreement with those obtained in several recent experiments. Based on the calculated results, an effective way to improve the photoluminescence efficiency in porous silicon is provided, and a model about the origin of luminescence in porous silicon is suggested.