PtSe₂ vdW single-crystal surfaces studied at the atomic scale with ncAFM

Abstract

Surfaces of van-der-Waals-bonded (vdW) single-crystal PtSe2 cleaved in ultrahigh vacuum (UHV) were studied with noncontact atomic force microscopy (ncAFM) at the atomic level. Typical ionic and electronic defects were characterized with single-atom precision: the identification of surface and subsurface defects was achieved by observing the atomic and electronic structure in parallel. The metallic single crystals exhibit a proclivity of the PtSe2 toward different defect types compared to the synthesized trilayer thin films of semiconducting PtSe2 and other Pt-based TMDs. Cleaved surfaces are representative of the commonly exfoliated flakes so further experiments with in situ deliberate stoichiometry adjustments and the adsorption of gasses will be presented. Additionally, the growth of a CaF2 dielectric on these surfaces will be demonstrated.