G-SIMS: relative effectiveness of different monatomic primary ion source combinations

Area of Science:

• Surface Science and Analytical Chemistry
• Mass Spectrometry
• Materials Characterization

Background:

• Secondary Ion Mass Spectrometry (SIMS) is a powerful surface analysis technique.
• Gentle SIMS (G-SIMS) aims to improve spectral quality by controlling ion emission.
• The parameter beta quantifies relative ion intensities in G-SIMS, crucial for spectral interpretation.

Purpose of the Study:

• To analyze the characteristics of monatomic primary ion sources for G-SIMS.
• To establish a predictive model for G-SIMS performance based on ion properties.
• To identify optimal primary ions for maximizing G-SIMS signal quality.

Main Methods:

• Analysis of G-SIMS spectra from polystyrene using various monatomic primary ions (Ar+, Bi+, Cs+, Ga+, Mn+, Xe+).
• Determination of the parameter beta, relating to emitted secondary ion fragment surface plasma temperatures.
• Development of an empirical fit correlating beta values with the ratio of sputtering yield and primary ion mass.

Main Results:

• Experimental beta values are accurately described by an empirical fit involving sputtering yield and primary ion mass.
• The model successfully integrates data for multiple monatomic primary ions across a range of energies (4-25 keV).
• Bismuth (Bi+) ions are predicted to yield the highest beta values, while Manganese (Mn+) ions yield the lowest.

Conclusions:

• A coherent framework is established for understanding monatomic primary ion performance in G-SIMS.
• The findings allow prediction of G-SIMS performance for any monatomic primary ion.
• Bismuth (Bi+) and Manganese (Mn+) ions are recommended for combined G-SIMS sources to achieve maximum signal quality.