Characterization of geometrical factors for quantitative angle-resolved photoelectron spectroscopy

For conventional angle-resolved x-ray photoelectron spectroscopy (ARXPS), the area under the core-level peaks depends mainly on the in-depth distribution of chemical species at the top surface of a specimen. But the x-ray photoelectron spectroscopy (XPS) intensity is also affected by tool-related geometrical factors such as the shape of the x-ray beam, the spectrometer analysis volume, and the manipulator rotation axis. Data analysis is therefore typically based on normalization with respect to the signal from the substrate. Here, we present an original method to perform quantitative ARXPS without normalization, involving evaluation of these geometrical factors. The method is illustrated for a multiprobe XPS system using a methodology based on a specific software (XPSGeometry (R)), but is a general process that can be adapted to all types of XPS equipment, even those not specifically designed for ARXPS. In that case, this method enables bringing the sample as close as possible to the manipulator axis of rotation in order to perform automatic acquisitions. (C) 2012 American Vacuum Society. [http://dx.doi.org/10.1116/1.4723827]