Quantitative depth distribution analysis of elements in high alloy steel using MCs+-SIMS approach

Abstract

Elemental composition analysis in alloy samples using secondary ion mass spectrometry (SIMS) suffers from matrix effects which hamper the analytical results. These matrix effects arise due to numerous factors like change in surface work function due to primary ion beam implantation, presence of reactive chemical species in the samples or on the sample surface, sample composition, chamber pressure etc. which changes the ionization probability of secondary ion species and hence produces non-linear effects in the production of secondary ions. In order to minimize these effects, Cs+ primary ion beam in conjunction with MCs+ (M being the element of interest) secondary ion monitoring (MCs+-SIMS) approach has been used. The MCs+-SIMS approach has been extensively used for quantitative depth distribution analysis in semiconductor samples but limited reports are available for the analysis of alloys sample. In the present work, the MCs+-SIMS approach has been utilized to determine the chemical composition and quantitative depth distribution of multiple elements (C, Si, Ni, Mn, Cr, Co, Mo and Fe) in high alloy steel samples. Quantitative depth distribution analysis revealed a non-homogenous distribution of elements on the steel surface which can be due to the presence of surface oxide layers. The minor and major constituents such as Cr, Mo; Mn, Ni; and Si; were determined with relative error of <2%, 6% and 5%, respectively. Surface distribution analyses of these elements were also carried out using both Cs+ and O2+ primary ion beams. An interesting and contrasting feature has been observed for surface distribution analysis carried out with MCs+ as compared to M+ secondary ion detection mode. It was observed that the surface distribution patterns of non-homogenous elements showed homogenous distribution patterns in case of MCs+ secondary ion monitoring approach. This anomaly can be attributed to the difference in formation mechanism of MCs+ and M+ secondary ions.