GaAs/AlAs superlattice as a proposed new reference material for sputter depth profiling

A GaAs/AlAs superlattice growth by metal–organic chemical vapour deposition is being proposed as the single crystalline multilayer reference material for sputter depth profiling. This material was characterized by transmission electron microscopy experiments, which showed that the interface between GaAs and AlAs is atomically flat. The preliminary depth profiling experiments were carried out by AES and SIMS. The AES experiments were performed using a Perkin‐Elmer SAM 660 scanning Auger microprobe and the SIMS experiments were carried out using a VSW multitechnique XPS/SIMS surface analysis system. The AES and SIMS sputter depth profiling experiments proved that the depth resolution was found to be almost constant for each interface when an Ar⁺ beam was used for sputtering. Therefore the sputtering‐induced roughness is very small for this material with Ar⁺ beam profiling, the depth resolution deteriorated as a function of depth, indicating oxygen ion beam‐induced surface roughening. For both AES and SIMS, the depth resolution improved for ion beams with lower kinetic energy and more glancing angles of incidence.