VISIBLE PHOTOLUMINESCENCE FROM LOW-TEMPERATURE DEPOSITED HYDROGENATEDAMORPHOUS-SILICON NITRIDE

Hydrogenated amorphous silicon nitride (a-SiNx:H) samples have been pr epared by plasma enhanced chemical vapor deposition (PECVD) using a mi xture of silane (SiH4), nitrogen and ammonia (NH3). Most films exhibit visible photoluminescence (PL) and some emit strong PL after annealin g. While films grown without NH3 exhibit PL in the deep red, those gro wn with NH3 show PL in the green. The PL properties of these films wit h no oxygen (O) content are similar to those of silicon oxide (SiOx) f ilms and porous Si. Using infrared and X-ray Photoelectron Spectroscop y, we suggest that PL from a-SiNx:H films originate from Si clusters w hich form during PECVD and crystallize upon annealing. We propose that the presence of O is not necessary for efficient PL.