DEPTH PROFILING OF AS IN AN ALAS/GAAS MULTILAYER BY A NEW LASER-INDUCED SPUTTERED NEUTRAL MASS-SPECTROMETRY SYSTEM

Depth profiling of As in an AlAs/GaAs multilayer has been measured with a pulse-counting photoion mass spectrometer (PPMS) that can perform depth profiling in two different modes: a secondary ion mass spectrometry (SIMS) mode and a laser-induced sputtered neutral mass spectrometry (SNMS) mode. In SIMS mode, the As secondary ion intensity in GaAs layers is about three orders of magnitude less than that in AlAs layers under O2+ bombardment even though the As concentration is the same in both layers. In SNMS mode, the As photoion intensity in GaAs is only about twice that in AlAs. This difference can be attributed to sputtering yield differences between GaAs and AlAs. This result suggests that laser-induced SNMS by PPMS will give quantitative information and accurate depth profiling of layered samples by simply correcting sputtering yields.