Atomic mixing, surface roughness and information depth in high‐resolution AES depth profiling of a GaAs/AlAs superlattice structure

High‐resolution AES depth profiling of a GaAs/AlAs superlattice structure with 8.8/9.9 nm single‐layer thickness by sputtering with 1.0 keV and 0.6 keV Ar + ions at an incidence angle of 80° resulted in optimum depth resolution values for 0.6 keV Ar + ions of Δ z = 2.0 nm for the low‐energy Al (68 eV) intensity profile and of Δ z = 2.0 nm for the high‐energy Al (1396 eV) intensity profile. A simple model description of the influence of atomic mixing ( w ), surface roughness (σ) and Auger electron escape depth (λ) was applied to calculate the measured profiles. An excellent fit is obtained by a reasonable set of these parameters: for 0.6 keV Ar + ion sputtering, w = 1.0 nm, σ = 0.6 nm, λ (Al 68 eV) = 0.4 nm and λ (Al 1396 eV) = 1.7 nm.