Exploring the growth and oxidation of 2D-TaSon Cu(111).

In this work, the growth and stability towards Oexposure of two dimensional (2D) TaSon a Cu(111) substrate is investigated. Large area (∼1 cm) crystalline 2D-TaSfilms with a metallic character are prepared on a single crystal Cu(111) substrate via a multistep approach based on physical vapor deposition. Analytical techniques such as Auger electron spectroscopy, low energy electron diffraction, and photoemission spectroscopy are used to characterize the composition, crystallinity, and electronic structure of the surface. At coverages below one monolayer equivalent (ML), misoriented TaSdomains are formed, which are rotated up to±13orelative to the Cu(111) crystallographic directions. The TaSdomains misorientation decreases as the film thickness approaches 1 ML, at which the crystallographic directions of TaSand Cu(111) are aligned. The TaSfilm is found to grow epitaxially on Cu(111). As revealed by low energy electron diffraction in conjunction with an atomic model simulation, the (3 × 3) unit cells of TaSmatch the (4 × 4) supercell of Cu(111). Furthermore, the exposure of TaSto O, does not lead to the formation of a robust tantalum oxide film, only minor amounts of stable oxides being detected on the surface. Instead, the exposure of TaSfilms to Oleads predominantly to a reduction of the film thickness, evidenced by a decrease in the content of both Ta and S atoms of the film. This is attributed to the formation of oxide species that are unstable and mainly desorb from the surface below room temperature. Temperature programmed desorption spectroscopy confirms the formation of SO, which desorbs from the surface between 100 and500 K.These results provide new insights into the oxidative degradation of 2D-TaSon Cu(111).