Surface analysis of contaminated GaAs: Comparison of new laser-based techniques with SIMS

A method of surface analysis by laser ionization (SALI) has been developed recently with an elemental sensitivity comparable to secondary ion mass spectrometry (SIMS). This mass spectrometric method uses intense UV laser general postionization following desorption or sputtering. The method has been applied to the analysis of a clean and contaminated GaAs(100) sample. Using an Ar+ beam for sputtering, direct comparison with SIMS shows the much more quantitative nature of SALI spectra. A 1.06-μm laser beam also was used to remove material for analysis, and comparisons are again made between desorbed neutral and ion species. Several potential uses of SALI are described for chemical analysis and for investigations of fundamental desorption mechanisms.