HAXPES Lab: A novel laboratory-based Hard X-ray Photoelectron Spectroscopy System

Hard X-ray photoelectron spectroscopy (HAXPES) uses X-rays in the 2-10 keV range to excite photoelectrons, which are used to non-destructively probe the local chemistry and electronic structure of materials. It is particularly useful as it can be applied to bulk as well as structured samples. HAXPES is a powerful technique for the study of buried layers and interfaces in multilayer thin film stacks and composite materials. Up to now HAXPES was only available at synchrotron sources, which provide the necessary intense, high energy X-rays.
This work presents a new laboratory-based instrument capable of delivering monochromated hard X-rays with an energy of 9.25 keV, giving an excellent energy resolution of <0.5 eV. The instrument behaviour and capability is showcased by experimental results from reference as well as technologically relevant systems, including TiO₂ bulk samples and multilayer metal oxide structures used in transistors. Measurements including shallow and deep core levels, Auger lines, and valence bands will be presented, including comparison of valence data with theoretical density of states calculations.