Si and N dangling bond creation in silicon nitride thin films

We observe the simultaneous creation of paramagnetic Si and N dangling bonds when N-rich silicon nitride thin films are optically illuminated at low temperatures (110 K). Generally, only the Si dangling bond is observed if the illumination is performed at room temperature. In contrast, 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 causes two processes: (1) Charge conversion of N 3≡Si+ and N3≡Si- sites to give two N3≡Sidangling bonds, and (2) charge transfer between Si2=N- and N3≡Si+ sites to form Si2=N and N3≡Sidangling bonds.