Sputter depth profiling of InN layers

Epitaxial InN layers have been investigated by means of sputter depth profiling with low energy argon ions in conjunction with Auger electron spectroscopy. We have proven that the incidence angle of the ion beam plays a crucial role in the sputter behaviour of InN and is very important for the proper sputter depth profiling procedure. The sputtering under normal incidence and at 60degrees with respect to the surface normal leads to a strong nitrogen depletion at the InN surface and the surface becomes rougher due to the build-up of indium droplets. Due to the increase of the roughness during sputtering, the sputter depth profiling measurements performed under such conditions provided broad interface regions. By an increase of the ion beam incidence angle up to 80degrees, metallization of the InN surface and creation of droplets were hindered. However, the surface appeared to be nitrogen depleted due to the sputtering under oblique incidence, too. Under this condition, smoothing of the InN surface was observed. This fact results in a sharp interface region between InN and AlN. We established the sputtering under grazing incidence angle as an appropriate tool for characterization of InN layers and their interfaces by means of sputter depth profiling. (C) 2003 Elsevier B.V. All rights reserved.