We observe the simultaneous creation of paramagnetic Si and N dangling
bonds when N-rich silicon nitride thin films are optically illuminate
d at low temperatures (110 K). Generally, only the Si dangling bond is
observed if the illumination is performed at room temperature. In con
trast, the N dangling bond is metastable, and has previously only been
observed after a high temperature post-deposition anneal and followed
by illumination. We propose that the low temperature illumination cau
ses two processes: (1) Charge conversion of N3=Si+ and N3=Si-sites to
give two N3=Si . dangling bonds, and (2) charge transfer between Si2=N
- and N3=Si+ sites to form Si2=N . and N3=Si . dangling bonds.