Systematics of secondary-ion-mass spectrometry relative sensitivity factors versus electron affinity and ionization potential for a variety of matrices determined from implanted standards of more than 70 elements

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Abstract
We have measured and plotted the dependence of secondary-ion-mass spectrometry (SIMS) relative sensitivity factor (RSF) on electron affinity and ionization potential of up to 74 elements implanted into 23 materials, measured using oxygen-ion bombardment and positive SIMS, and cesium-ion bombardment and negative SIMS. Reproducibility of ±60% in RSF has been demonstrated for many of these implanted standards over a period of 8 years in several Cameca magnetic sector instruments, especially in Si, GaAs, and HgCdTe matrices. More recently, reproducibilities of ±20%–30% have been achieved using more controlled experimental techniques. Similarities among plots of logRSF versus ionization potential or electron affinity have been found for a variety of semiconductor, metal, and insulator matrices. Universal patterns and trends are observed for oxygen bombardment and positive SIMS, and for cesium bombardment and negative SIMS. Four major regions are seen in the dependence of logRSF on ionization potential, one with possibly three branches with slightly differing slopes, that are characterized by elements from various groups of the periodic table. There are two major regions in the plots of RSF versus electron affinity, one of which is a region of constant RSF versus electron affinity, which includes the more electronegative elements, and meaning that the RSF is a constant for most of the elements commonly analyzed using negative (cesium) SIMS. This constant RSF has been measured for 20 matrices. We report the values of slope of logRSF versus ionization potential for the matrices studied and discuss the possible extension to other matrices. We tabulate the values of RSF for 74 elements in Si and for 69 elements in GaAs, as examples. Tentative explanations of the features of these dependencies are consistent with existing theories and models. We give generalized patterns of RSF (ion yield) versus ionization potential or electron affinity and an equation from which RSFs can be calculated for the matrices studied, and possibly others.

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