Defect-based model for room-temperature visible photoluminescence in porous silicon

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Abstract
Electron-spin resonance and photoluminescence (PL) experiments have been performed on porous silicon. Results indicate the presence of oxygen shallow donors of binding energy in the 0.1-eV range, which show a distinct correlation with the intensity of the red PL observed in porous silicon. It is suggested that the shallow donors become paramagnetic by photoinduced capture of carriers created by light absorption in the silicon crystallites. A model is suggested that links the presence of the shallow donors to the presence of nonbridging oxygen hole centers, which are thought to be responsible for the intense red PL reported in porous silicon.