Elimination of the secondary electron background in Auger electron spectroscopy using low energy positron excitation

Abstract

Data is presented which demonstrate that positron annihilation‐induced auger electron spectroscopy (PAES) can be used to eliminate secondary electrons in the energy range of Auger electrons. In PAES the core–hole excitations necessary for Auger electron spectroscopy (AES) are created by annihilation of core electrons using low energy (<25 eV) positrons. Secondary electrons cannot be created through collisional processes with energies in excess of an energy Ek≊Ep (the primary beam energy). Spectra obtained for a Cu (110) surface demonstrate that Auger signals can be obtained with peak‐to‐background ratios in excess of 50:1 (more than two orders of magnitude improvement over conventional electron excited Auger methods). PAES spectra obtained from Cs‐covered Cu surfaces are used to place upper limits on the relative contribution of gamma‐ray induced secondary electrons to the PAES background. Implications of the high signal‐to‐background ratios obtained using PAES for increasing the elemental sensitivity and reducing beam damage of AES are discussed.