The energy band gap of light-emitting porous silicon is determined by high-resolution electron energy loss spectroscopy, and the valence band edge of porous silicon with respect to its Fermi level is measured by ultraviolet photoelectron spectroscopy. By combining the results with that measured from clean Si, a picture of band lineup at the porous-silicon/p-Si heterointerface is proposed, in which 70% of the total band gap discontinuity occurs at the valence band edge.

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