The role of argon in plasma-assisted deposition of indium nitride

Radiofrequency (RF) nitrogen plasma sources are commonly employed in the growth of group III-nitrides by molecular beam epitaxy and reactive evaporation. These sources produce atomic nitrogen and excited molecules (N₂*). In this work the relative flux of these two species produced by an RF source was studied by emission spectroscopy as a function of power, pressure, and argon dilution. Polycrystalline indium nitride thin films were synthesized under the same conditions. It was found that argon dilution had a strong influence on the production of active nitrogen, with maximum fluxes obtained around ∼40% N₂. Film properties, as measured by X-ray diffraction, atomic force microscopy and Hall effect, were also optimized at this condition. It was observed that the Hall mobility scaled with the sum of N and N₂* emission, suggesting that both species may be beneficial for InN growth.