Dependence of depth resolution on primary energy of low-energy Ar+ Ions (100-1000 eV) in AES sputter depth profiling of GaAs/AlAs superlattice

摘要

The dependence of the depth resolution on the primary energy of low-energy Ar+ ions in Auger electron spectroscopy (AES) sputter depth profiling of an ISO reference material GaAs/AlAs superlattice was investigated for the ion incidence angle of 50 degrees from the sample surface normal. The depth resolution was found to improve as the square root of the primary energy of the ions as the primary energy decreased from 1000 to 200 eV. In contrast, a deterioration of the depth resolution was observed at 100 eV, which was induced by the difference in the etching rates between GaAs and AlAs and preferential sputtering. Further investigation of AES sputter depth profiling under irradiation of 100-eV Ar+ ions at the incident angle of 70 degrees revealed that the difference in the etching rate and preferential sputtering could be suppressed by changing the incident angle from 50 degrees to 70 degrees, leading to a depth resolution of similar to 1.3 nm with 100 eV. The present results confirmed that glancing incidence is effective in achieving higher depth resolution from the point of view of the reduction of not only atomic mixing but also the difference in the etching rates and preferential sputtering. Careful attention is required for optimizing conditions of low-energy ion irradiation in sputter depth profiling using the GaAs/AlAs reference material. Copyright (C) 2006 John Wiley & Sons, Ltd.