Depth-Resolved Photoemission Spectroscopy From Surface and Buried Layers with Soft X-ray Standing Waves

Abstract

A new type of depth-resolved soft X-ray photoemission spectroscopy (SXPS) is carried out in which depth sensitivity is provided by means of a periodic multilayer {[B4C(22.5 Angstrom)-W(17.1 Angstrom)](40)} that possesses sizeable standing wave effects of +/- similar to 50-60% for soft X-rays at hv approximate to 750 eV. The photoelectron intensities of each element in the sample, including impurity overlayers, are sharply altered when the incidence angle is tuned over the Bragg condition, in excellent agreement with theoretical simulations. The angular dependence of photoelectron intensity also shows unique chemical-state-resolved behavior depending on the location of a given species in the multilayer structure. Depth-resolved SXPS with soft X-ray standing wave excitation should thus be a very useful tool for studying surface and interface chemical, electronic, and magnetic properties. (C) 2000 Elsevier Science B.V. All rights reserved.