Ultrathin epitaxial Bi film growth on 2D HfTe2 template

Among ultrathin Monoelemental 2D Materials (ME2DMs), bismuthene, the single layer of heavier group-VΑ element bismuth (Bi), has been predicted to have large non trivial gap. Here, we demonstrate the growth of Bi films by molecular beam epitaxy (MBE) on 2D-HfTe2template. At the initial stage of Bi deposition (1-2 bilayers, BL), both the pseudocubic Bi(110) and the hexagonal Bi(111) phases are formed. When reaching 3 BL Bi, a transformation to pure hexagonal Bi(111) occurs. The electronic band structure of 3BL Bi(111) films was measured by Angle-Resolved Photoemission Spectroscopy (ARPES) showing very good matching with the Density Functional Theory (DFT) band structure calculations of 3BL free standing Bi(111). The grown Bi(111) thin film was capped with a protective Al2O3layer and its stability under ambient conditions, necessary for practical applications and device fabrication, was confirmed by XPS and Raman spectroscopy.