Quantitative secondary ion mass spectrometry analysis of impurities in GaNand AlxGa1-xN films using molecular ions MCs+ and MCs2+

In SIMS analysis of GaN and AlxGa1-xN films, MCs+ and MCs2+ ion detection ( M is the element to be analyzed) was investigated under Cs+ bombardment. Th e MCs2+ ions have a larger ion yield than the MCs+ ions when M is one of el ectronegative ions. Application of these molecular ions to SIMS analysis ha s made it possible to detect electropositive and electronegative elements i n a single analysis run. Further, these molecular ions are useful to minimi ze the matrix effect in AlxGa1-xN films, with x ranging from 0 to 0.17. The formation mechanism of the MCs+ and MCs2+ ions can also be postulated by c omparing the useful yield of these molecular ions and that of single (negat ive and/or positive) ions. These molecular ions are assumed to be produced mainly by recombination processes in which sputtered neutral species (M and /or MCs) combine with Cs+ ions. (C) 1999 Elsevier Science B.V. All rights r eserved.