SIMS matrix effects in Alx Ga1 – xAs: Influence of instrumental parameters

Abstract

AbstractThe influence of instrumental parameters on the matrix effects (ion and sputtering yield variations) observed in AlxGa1 – xAs are critically evaluated. Ion and sputtering yield data from three different SIMS instruments (ARL IMMA, Cameca IMS‐3F and Atomika SIMS) are examined. The influence of primary ion (O2 +) energy and incident angle on the extent of surface oxidation was examined using AES. Although relative ion yields varied linearly with the matrix composition in all instances, these ion yield variations differed greatly (a factor of 50) between instruments. These differences were attributed to differences in the surface oxygen concentrations produced by the SIMS instruments. AlAs was shown to be completely oxidized under each of the SIMS ion bombardment conditions. However, the oxygen levels incorporated in GaAs and the other Al poor specimens depended largely on the incident angle and to a lesser extent on the ion energy. Small incidence angles (normal incidence) promoted the most extensive oxidation of the Al‐poor specimens, resulting in the smallest ion yield variations with matrix. As with the relative ion yields, relative sputtering yields varied linearly with the matrix composition in all instances. However, in contrast to relative ion yields, the relative sputtering yields did not change significantly under the different instrumental conditions. It was concluded that incident angle and ion energy had approximately the same influence on the sputtering yields obtained from the reference and the sample matrices. Thus, the relative sputtering yields were insensitive to changes in these ion beam parameters.