Electron spin resonance of substitutional nitrogen in silicon

The development of silicon-based nanoscale technology for the realization of single electron, single spin quantum devices demands deep donor-based systems to achieve a major breakthrough in the field: high-temperature operation. Here, we suggest that, despite some preparation difficulties, substitutional nitrogen in silicon (N_{Si}) represents an interesting candidate for this purpose, being observable by electron paramagnetic resonance (EPR) at room temperature. We report a study of the nature and dynamics of substitutional nitrogen in silicon, the so-called SL5 paramagnetic center, by X-band continuous-wave EPR, complemented by pulsed EPR. Both natural and ^{28}Si isotopically enriched nitrogen-doped silicon samples have been used, the latter providing an improvement in the accuracy of the spin Hamiltonian parameters.