Sputtering behavior and evolution of depth resolution upon low energy ion irradiation of GaAs

The authors have investigated the sputtering behavior and evolution of depth resolution upon low energy ion irradiation during secondary ion mass spectrometry (SIMS) depth profiling of GaAs. They presented a systematic and quantitative study of the impact of ion species, primary ion impact energy, and incident angle on (evolution of) depth resolution using a well-characterized dedicated InGaAs/GaAs multilayer structure with nearly atomically abrupt heterointerfaces. They demonstrated that for low energy O-2(+) ion beam irradiation, the SIMS depth resolution is severely degraded by (transient) incorporation of high surface O-concentration into the altered layer, leading to detrimental ion beam induced formation of topography. They provided evidence that topography formation is primarily invoked by the strong angular dependence of the sputter yield on (local) incident angle. In the case of low energy, oblique Cs+ ion beam irradiation, the sputtering behavior of GaAs is well-behaved with no significant transient yield changes and a constant depth resolution. This enables SIMS depth profiling of sharp heteroepitaxial III-V multilayer structures and shallow dopant profiles with sufficiently good depth resolution and good detection efficiency. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3514117]