Quantitative X-Ray Emission Analysis of Thin Oxide Films on Tantalum

Abstract

A low-energy (1800-V) electron beam is used at normal incidence to excite the characteristic x-ray emission from oxygen in thin oxide films on smooth tantalum substrates. From films having known thickness increments, a calibration procedure is used to relate the oxygen Kα signal/background ratio to oxygen concentrations in the films. Films ranging from less than one monolayer to several hundred Å mean thickness can be measured. At the submonolayer level, oxygen concentrations of about 1×10−9 g cm−2 can be detected on a tantalum surface.