Directional Auger Electron Spectroscopy - Possibilities, Limitations and Proposal of Improvements

Abstract

Physical foundations of directional auger electron spectroscopy (DAES) and calculation of DAES profiles in single scattering cluster approach are presented. Limitations of this method (application only to investigation of the crystalline structure of homogeneous samples) is shown and explained as the result of participation of inelastically scattered electrons in the Auger signal generation. To extend the DAES application for the interface structure, the use of as low as possible energy of primary electrons is proposed because in such a case the participation of inelastically scattered electrons becomes negligible and single scattering cluster calculation should describe correctly the DAES profiles for interfaces. Besides, the extension of single scattering cluster calculations to the second elastic scattering is recommended. To check the technical possibility of DAES use in the proposed version, the Auger spectrum of Cu LM M peaks was recorded for a Cu 3 Au(001) sample with the use of a retarding field analyzer with the primary beam energy 1200 eV. Quality of this spectrum seems to be good enough for using in DAES.PACS numbers: 61.05.J-, 68.35.Rh Description of DAES method and SSC approximationThe influence of the primary electron beam direction on the Auger signals measured for crystalline samples is well recognized for many years (see, for example, reviews [1, 2] and references therein). Namely, distinct maxima of the measured Auger signal appear when the primary electron beam is parallel to the direction of some set of close packed rows of atoms in the crystal investigated. This opportunity was seen as the difficulty in a quantitative Auger analysis. On the other hand, it was used as a base of the method giving information about the crystalline structure of ultrathin layers and about the epitaxial relation between the deposited layer and its substrate (directional Auger electron spectroscopy -DAES in [3] and primary-beam diffraction-modulated electron emission -PDMEE in (S-93)