Quantitative measurement of impurities in GaAs layers by secondary ion mass spectrometry

A quadrupole‐based SIMS system has been used for the localized impurity analysis of GaAs. Spectral interferences are reduced by using a mass filtered primary ion beam and UHV conditions in the target chamber with energy discrimination of the secondary ions. Practical detection limits for 12 elements have been determined with samples calibrated by other methods. Detection limits for important impurities in GaAs range from 10 14 atoms cm −3 for Cr and Mn to 10 16 atoms cm −3 for Si, Zn and Sn. Depth profiles are presented which demonstrate that this detection capability is attained with micron thick layers. Confirmatory evidence of profile shapes and impurity concentrations has been obtained from independent electrical data.