Charge-state changes of substitutional nitrogen impurities in silicon induced by additional impurities and defects

Abstract
Charge states of substitutional N impurities (Ns) in Si are found to be controllable by doping with P, B, and O impurities in N-ion implanted and subsequently pulsed-laser annealed Si (Si:N system). Electron-spin resonance measurements of the Si:N system doped with P, B, or O impurities show that the spin density of neutral Ns (N0s) decreases because of doping with these impurities. Compensation by multiple doping with equal amounts of P and B impurities leaves the density of N0s essentially unchanged. These results yield evidence for charge-state changes of Ns due to the Fermi level shift. Oxygen doping is found to introduce donors. Three charge states, i.e., positive (N+s) , neutral (N0s) , and negative (N−s) are assigned to off-center substitutional N in Si.