Photoluminescence (PL) spectra of partially oxidized porous Si (POPS) coate
d 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 similar to 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). S
i coating mainly leads to introduction of the NBOHCs defects and thus makes
the PL intensity enhanced. The blueshift of similar to 60 meV is a result
of the local equilibrium of NBOHCs defects under high temperature. (C) 2000
American Institute of Physics. [S0021-8979(00)07019-5].