Enhanced and stable photoluminescence from partially oxidized porous Si coated with Si thin films

Photoluminescence ~PL! spectra of partially oxidized porous Si ~POPS! coated with Si thin films were examined using the 488 nm line of Ar laser. The obtained PL is stable, peaks at 1.763 eV with a blueshift of ;60 meV, and its maximal intensity is seven times larger than that of the POPS. Spectral analysis and the experimental results from infrared spectroscopy and electron spin resonance suggest that the enhanced and stable PL arises from optical transitions in the nonbridging oxygen hole centers ~NBOHCs!. Si coating mainly leads to introduction of the NBOHCs defects and thus makes the PL intensity enhanced. The blueshift of ;60 meV is a result of the local equilibrium of NBOHCs defects under high temperature. © 2000 American Institute of Physics. @S0021-8979~00!07019-5#