Spectroscopic ellipsometry studies of reactively sputtered nitrogen-rich GaAsN films

► Nitrogen-rich GaAsN thin films of variable arsenic content have been deposited by reactive rf sputtering of GaAs target. ► Films deposited with 12-100% nitrogen in the sputtering atmosphere are primarily polycrystalline hexagonal GaN with GaN-like optical parameters. ► Films deposited with less than 40% nitrogen show disorder related effects, arising from the increase in arsenic-rich amorphous phase. ► Films deposited in a narrow range of 5-12% nitrogen show effects due to the incorporation of arsenic in the lattice and the consequent formation of polycrystalline GaAsxN1−x alloy films.