We demonstrate that ambient pressure X-ray photoelectron spectroscopy (APXPS) can be used for in situ studies of dynamic changes in surface chemistry in a plasma environment. This opens a new and vast application space for XPS and greatly complements modern spectroscopy techniques to probe plasma–solid/liquid interactions relevant to process monitoring in the semiconductor industry, biomedical plasma applications, and plasma remediation technologies. Hexagonal boron nitride (h-BN) grown on Cu was used in this study as a well-defined model system for plasma process monitoring because of its unique chemical, optical, and electrical properties that make it a prospective material for advanced electronics. To better understand the stability and surface chemistry of h-BN during plasma-assisted processing, we track in real time the plasma-induced chemical state changes of B, N, and the underlying Cu substrate using APXPS equipped with an AC discharge plasma source operating at 13 Pa. Residual gas analysis mass-spectra were concurrently collected during plasma-XPS to track reaction products formed during plasma exposure. A clear reduction of CuxO is seen, while an h-BN layer remains intact, suggesting that hydrogen radical (H•) species can attack the exposed and h-BN-covered Cu oxide patches and partially reduce the underlying substrate without significantly damaging the overlaying h-BN, which is of practical importance for development of h-BN-encapsulated devices and interfaces. In addition to demonstration of plasma-XPS capabilities, we discuss the observed challenges (e.g., parasitic plasma-chamber wall reactions and charging effects) and propose potential solutions.
Xenon Trapping Xenon (Xe) atoms are trapped in silicate nanocages in contact with a metal surface. The atoms can be trapped at moderate temperatures (> 300 K) and released by heating to elevated temperatures (> 750 K). This can benefit several applications, including Xe production, nuclear power, nuclear waste remediation, and nonpro liferation of nuclear weapons. More details can be found in article 2103661 by Matheus Dorneles de Mello, J. Anibal Boscoboinik, and co-workers.
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