We have demonstrated a stimulated photoluminescence (PL) at 694 and 692nm whose emission peak has a Lorentzian shape with a full width at half maximum of 0.5–0.6nm. This stimulated emission comes from the nanostructures on porous silicon oxidized fabricated by irradiation and annealing treatment. Controlling the time of annealing can produce a good coherent emission. A model has been proposed for explaining the stimulated emission in which the trap states of the interface between oxide of silicon and porous nanocrystal play an important role. Calculation shows that trap electronic states appear in the energy gap of the smaller nanocrystal when SiO bonds or Si–O–Si bonds are formed. In the theoretical model, the most important factor in the enhancement and pinning effect of PL emission is the relative position between the level of the trap states and the level of the photoexcitation in the silicon nanocrystal.

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The photoluminescence (PL) of nanocrystal present in porous silicon shifts from the near infrared to the ultraviolet depending on the size when the surface is passivated with Si-H bonds. After oxidation, the centre wavelength of PL band is pinned in a region of 700–750 nm and its intensity increases obviously. Calculation shows that trap electronic states appear in the band gap of a smaller nanocrystal when Si = O bonds or Si–O–Si bonds are formed. The changes in PL intensity and wavelength can be explained by both quantum confinement and trap states in an oxidation layer of nanocrystal. In the theoretical model, the most important factor in the enhancement and the pinning effects of PL emission is the relative position between the level of the trap states and the level of the photoexcitation in the silicon nanocrystal.

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Stimulated photoluminescence (PL) emission has been observed from an oxide structure of silicon when optically excited by a radiation of 514nm laser. Sharp twin peaks at 694 and 692nm are dominated by stimulated emission, which can be demonstrated by its threshold behaviour and linear transition of emission intensity as a function of pump power. The oxide structure is formed by laser irradiation on silicon and its annealing treatment. A model for explaining the stimulated emission is proposed, in which the trap states of the interface between an oxide of silicon and porous nanocrystal play an important role.