NEW NITROGEN-RELATED DEFECTS IN NITROGEN-RICH A-SIXN1-X-H

Previous electron spin resonance (ESR) measurements in device-quality, nitrogen-rich a-Si(x)N1(1-x):H have identified only one defect - a da ngling bond on a three-fold-coordinated silicon that is back-bonded to three nitrogen atoms (K center), The identification is reported of a second, nitrogen-related defect (N-2 center) whose density is essentia lly the same as that of the K center but whose presence in the ESR spe ctra can only be identified unambiguously at low temperatures (4 K) an d high microwave powers. This new signal is very difficult to distingu ish from that of the K center at most temperatures. Computer simulatio ns indicate that the N-2 center is a dangling bond on a two-fold-coord inated nitrogen and that the ratio of the intensities of the K and N-2 centers is approximately 1:1. These results and those previously obta ined using photoluminescence (PL), PL fatigue, bleaching of fatigued F L, and PL excitation spectroscopy are most easily explained using a mo del that assumes charge redistribution within equal densities of pre-e xisting K+ and N-2(-) centers where both centers are assumed to have p ositive, effective electron-electron correlation energies (positive U- eff).