The research of visible luminescence from silicon-based materials is very important in the optoelectronic applications. The indirect band gap structure of bulk silicon decreases the efficient light emission obviously. But in silicon nanostructures

optical transitions rates are very high. Because of quantum confinement effect

photoluminescence originated from silicon nanostructures can be observed. So the silicon nanostructures have received consi-derable attentions. Films of hydrogenated silicon nitride (SiN

x

:H) have been prepared by plasma enhanced chemical vapor deposition (PECVD) technique at low temperature. Strong room-temperature photoluminescence has been observed in the films annealed at low temperature (300℃). The analysis of XPS indicates the existence of the Si clusters in the silicon nitride films. From the IR spectra

for the annealed samples

there is a first decrease of the Si—Habsorption peak intensity followed by a increase when the annealing temperature is more than 700℃. When the annealing temperature reaches 900℃

the PL peak with respect to the Si dangling bonds disappears

and there is a significant blueshift of the intense PL peak from the Si clusters in the spectra. In terms of Raman scattering spectra

the size of the Si clusters has been calculated in order to illuminate the reason of the photoluminescence blueshift. In terms of all the results

the intense visible photoluminescence is attributed to the existence of the Si clusters embedded in the silicon nitride matrix.