Hard X-ray photoelectron spectroscopy (HAXPES) in material development

X-ray photoelectron spectroscopy is a powerful method to investigate the chemistry of surfaces and buried interfaces which are critical for batteries, solar cells, etc. As the energies of the excited electrons are not high enough to travel through the material to the detector. Hard X-rays have been increasingly useful in this field [1] due to the higher photon energies and significantly increased information depth. Scienta Omicron’s HAXPES Lab uses a monochromatic Ga Ka metal jet source, enabling artefact-free investigations with superior information depth. Combined with a hemispherical electron analyzer with a ±30 degree acceptance angle [2], investigation of buried interfaces, operando devices and real world samples becomes easily achievable. [3]

This presentation will give an overview of HAXPES applications with a focus on buried interfaces in electronic devices. Nanoparticles typically consist of a core surrounded by a protective shell, e.g. passivation layer in quantum dots for optoelectronics and bioimaging. The shell thickness and chemical composition highly influence the material properties. Herein, a series of PTFE nanoparticles with PMMA shell was investigated (nominal shell thicknesses between 4.5 and 35.5 nm). The core material was detected even for particles with greatest shell thickness using Ga Kα HAXPES.

[1] Kalha, J. Phys. Condens. Matter., 33 (2021) 233001.; [2] B. Spencer, Faraday Discuss., 236 (2022), 311; [3] T. Hashimoto, Vac. Surf. Sci. 64 (2021) 493.