SIMS analysis of Al_xGa_1–xas/gaas layered structures grown by metal‐organic vapour phase Epitaxy

For Al_xGa_1‐xAs/GaAs layered structures, grown by MOVPE, abrupt interfaces in the order of one atomic distance were observed. These structures are well suited to serve as test samples for studying the influence of bombardment conditions on the quality of SIMS depth profiles. The results of such a study are presented and it is shown that depth profiles can be obtained with a depth resolution of about 25 Å. It was found that beyond the interface secondary ion signals decrease exponentially; from the variation of the slope of this exponential decay as a function of primary ion energy it can be concluded that depth resolution is determined by a purely collisional mixing process. From this type of data we can derive a minimal layer thickness in Al_xGa_1‐xAs/GaAs quantum well structures for which quantitative SIMS analysis of the Al content is possible.