Sputtering Behavior and Evolution of Depth Resolution upon Low Energy Ion Irradiation of GaAs

Abstract

We investigate the sputtering behavior and depth resolution upon low energy ion irradiation during Secondary Ion Mass Spectrometry (SIMS) depth profiling of GaAs. We present a systematic and quantitative study of the impact of ion species, primary ion impact energy, and incident angle on the evolution of depth resolution, using a well-defined InGaAs/GaAs multilayer structure with highly abrupt hetero-interfaces. We demonstrate that for low energy O2+ ion beam irradiation, SIMS depth resolution becomes progressively degraded by (transient) incorporation of high surface O-concentration levels in the altered layer, leading to detrimental ion-beam induced formation of topography. In case of low energy oblique Cs+ ion beam irradiation, 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 hetero-epitaxial III-V compound semiconductor structures and shallow dopant profiles with sufficiently good depth resolution with good detection efficiency.