Nondestructive Depth Profiling by Electron Spectroscopy with a Tuned Energy Excitation Source

Abstract

A novel nondestructive layer-by-layer method of chemical analysis that can be realized in an ordinary electron spectrometer is proposed. This method is based on the ionization spectroscopy (IS) and involves two sequential operations: a) collection of a series of experimental IS spectra taken at various primary beam energies; and b) recovering of the true concentration or phase depth profile using a reconstruction procedure that involves a mathematical treatment of these spectra. The proposed method was used to study the behavior of a FeNi 3 (100) alloy at temperatures close to the order-disorder transition temperature (T or ¼ 776 K). Using the reconstruction procedure, an oscillatory concentration profile in ten upper layers of FeNi 3 (100) alloy was obtained. The proposed method was also used in an investigation of the temperature dependence of the composition in the first ten layers of the Co 50 Ni 50 (100) alloy. In the temperature range 900 to 1200 K, the composition of all analyzed surface layers stabilized and remained the same, consisting of pure cobalt in the first layer, with its concentration decreasing in the three underlying layers to 82, 68 and 55 at%, respectively. These results correlate with LEED analysis that also had shown the existence of an hcp Co phase at the Co 50 Ni 50 (100) alloy surface.

Anisotropy in thermal oscillations of CoNi3 surface atoms

“…3) with data for nickel concentration C Ni in ten surface layers of CoNi 3 (100), (110) and (111) ( Fig. 4) (data obtained using IS and a recovering procedure [11]) confirmed the assumption. For the (100) plane of CoNi 3 alloy, the surface segregation is stronger than for the (111) plane.…”

“…The IS and AES spectra were collected by a cylindrical mirror analyzer. A novel nondestructive method of a layer-by layer surface compositional analysis was used that is based on IS and involves two sequential operations [11]: a) Collection of a series of experimental spectra taken at various primary beam energies, b) Recovery of the true concentration or phase depth profile using a reconstruction procedure that involves a mathematical treatment of these spectra.…”