X-ray emission by electron impact as a surface characterization tool for the light elements B, C, N and O: sensitivity factors and effective attenuation length

Abstract

X-ray emission induced by electron impact is a common characterization technique associated to electron microscopy. The possibility of employing this technique for surface and thin film analysis arises from the low energy electrons required to excite the inner shell transitions of the light elements, and is a field not sufficiently explored. In this work, we have studied experimentally the X-ray emission intensities from h-BN, B₄C and B₂O₃ bulk samples to determine the sensitivity factors (also known as k-factors) of the light elements C, N and O relative to B as a function of the incident electron beam energy. Furthermore, evaporated carbon thin films grown on Si(100) with thicknesses in the 20–200 nm range were used to derive the effective attenuation length λ(E) of the technique. In this way, and following a classical surface analysis approach, a fast and simple quantification procedure is presented to determine the composition of any compound of the B–C–N–O family in thin film form. These results have been compared with Monte Carlo simulations.