A NEW PORTRAYAL OF ELECTRON AND HOLE TRAPS IN AMORPHOUS-SILICON NITRIDE

Trap centers in amorphous silicon nitride (a-SiNx) have been considered to be amphoteric. We found two signals of Si3 3/4 Si 0 and N3 3/4 Si0 (Si dangling bonds with an unpaired electron) by an electron-spin-resonance method, and estimated the hole trap density to be larger than the electron trap density by about one decade, using the nonvolatile memory devices. As a result, we propose a new portrayal in which electron/hole traps are at the interface between Si clusters and a-SiNx bulk, and hole traps are at nitrogen vacancies in a-SiN x bulk.