Hydrogen radical induced Zn transfer to Ru film surfaces and influence of ambient atmosphere exposure on Zn adsorbates on Ru

In this article, for the first time, we report the transfer of Zn from contaminated walls in an ultra-high vacuum chamber to Ru film surfaces, induced by hydrogen radicals. In the presence of atomic H, Zn forms volatile Zn hydrides. We propose that Ru acts as a catalytically active surface for decomposing Zn hydrides, which leads to adsorption of Zn on Ru. The this way deposited Zn layer is nearly atomically flat with no specific surface morphology. The kinetics of adsorption and etching varies with the amount of adsorbed Zn. We hypothesize that the change in the Ru electronic structure, the charge transfer from Ru to Zn, and the availability of Ru active sites play a role. 0.7 Zn monolayer (ML) formed ∼ 1 ZnO ML after ambient atmosphere exposure. This ZnO layer prevents Ru oxidation and samples showed no morphology change of the Zn deposit upon storage in ambient atmosphere for 6 weeks. Ru surfaces with ≤ 0.8 ZnO ML showed conversion of a 2D layer of Zn adsorbates to 3D agglomerates, accompanied with native oxide formation on Ru. Observations may find use in the development of contamination mitigation strategies, metrology, and fabrication of 2D materials.