Auger Depth Profiling of a GaAs/AlAs Superlattice Structure by Using Factor Analysis

Abstract

Factor analysis and Auger electron spectroscopy (AES) were applied to the high resolution depth profiling of a GaAs/AlAs Superlattice grown by metal-organic chemical vapor deposition. Factor analysis was found to be utilized very successfully to extract clearly the depth profile of GaAs/AlAs interfaces from low energy Auger spectra (22∼70eV) containing overlapped peaks of Ga (MMM) and Al (LMM). Since the depth resolution Δz was found to be almost constant for every interface, the sputtering induced roughness was considered to be very small. From the experiments with various Ar⁺ ion energies E_iO (0.5∼3.0 keV), the depth resolution Δz was found to increase linearly with increasing E_iO following the relation (Δz=z₀O+kE_iO). From the comparison of depth profiles obtained from low and high kinetic energy regions, it was suggested that the interface profiles analyses from several different energy regions could give some useful informations about the energy dependency of inelastic mean free path.