Aluminum Oxide Films and Sapphire Demonstrate Interaction of Sample Preparation and Instrumentation for XPS Measurements of Layered Materials

Layered materials have multiple applications in electronics and energy storage, including gate dielectrics, diffusion barriers, surface coatings, and other devices. X‐ray photoelectron spectroscopy (XPS) is often used to characterize the chemistry of layered materials. However, before meaningful analysis of materials can be made by XPS, there is a need to investigate how a particular sample interacts with XPS instrumentation. Thin aluminum oxide films are promising optoelectronic materials due to their optical, chemical, and electrical properties. In this work, an example of aluminum foil is used to demonstrate the consequences of choices made when XPS is performed on a material with an oxide overlayer on a bulk metal substrate. The results presented demonstrate how these choices alter the spectra measured, and through extended periods of acquisition cycles, the response of a sample to XPS can be characterized, understood, and mitigated by experimental design and appropriate peak model construction.