GaAsN formation by implantation of nitrogen into GaAs studied by infrared spectroscopy

Fourier transform infrared absorption measurements of nitrogen-implanted GaAs layers have been carried out for studying the incorporation of nitrogen into the lattice. Samples are implanted with different ion energies providing nitrogen concentrations up to 2.2x1020 cm-3 (x=0.01) and annealed in the temperature range between 450 deg. C and 900 deg. C. The substitutional nitrogen fraction is determined by the strength of the local vibrational mode due to isolated nitrogen, NAs, at 471 cm-1. In samples implanted at low temperature, almost 100% activation of nitrogen can be achieved, although the observed line broadening is indicative of residual irradiation damage. An additional small band at 638 cm-1 is attributed to a nitrogen-gallium vacancy complex