Phase transition from Au–Te surface alloy towards tellurene-like monolayer

Abstract

Two-dimensional (2D) chalcogen-based layers have proven to be the next generation of materials for potential high-tech applications, and it is very important to control their properties at the nanoscale. Herein, we discuss the structural and electronic properties of Au(111) surface after being exposed to high temperature vapor deposition of Tellurium (Te) in ultrahigh vacuum. The scenarios entailing the formation of 2D AuTe2 metal dichalcogenide or rather Au–Te alloy monolayer (ML) or even Tellurene single layer deserved to be addressed. In this purpose, low energy electron diffraction (LEED) supported by scanning tunneling microscopy (STM) shows the existence of several surface reconstructions depending on the Te film thickness in the sub-monolayer regime. We observed that the well-known spin-split Shockley state of the Au(111) surface survives the Te deposition and is even shifted to higher binding energy, suggesting a charge transfer at the interface. For a coverage of 0.33 ML of Te, new dispersive bands are observed by angle-resolved photoemission (ARPES), which arise from a strong hybridization between the electronic states of Te and Au. With a substantially low intensity and a back-folding at the boundaries of the reduced surface Brillouin zone (R-SBZ), these electronic bands represent a proof of the existence of a naturel 2D electron gas, strongly disturbed by the surface reconstruction. It is therefore possible that an Au–Te alloy is formed at the surface. By increasing the coverage to 0.5 ML, a rich, thickness-dependent transition develops from the surface alloy to Tellurene-like structure and completely excludes the growth of AuTe2 monolayer. Both the surface alloy and the Tellurene monolayer have a semiconductor character with a gap in the occupied states of about 0.65 eV.

Atomic and mesoscopic structure of Dy-based surface alloys on noble metals

“…Surface alloys can be fabricated with long-range order and high structural quality on noble metal (NM) surfaces by replacing surface atoms of the NM host materials with different kinds of metallic guest atoms. This allows the investigation of bonding mechanisms for otherwise immiscible metals and to design the spin-dependent band dispersion of surfaces states [5][6][7][8][9][10][11].…”

Large Area Growth of Silver and Gold Telluride Ultrathin Films via Chemical Vapor Tellurization

“…Moreover, there are almost no reports on AuTe 2 chemical vapor deposition (CVD) growth on a large-scale. Recently, 2D Te growth on Au (111) substrates using molecular beam epitaxy has been reported, where the possible scenarios occurring between Te and Au, including the formation of compound AuTe 2 , toward the formation of monolayer tellurene on the Au substrate are discussed [25].…”

New Alloy of an Al-Chalcogen System: AlSe Surface Alloys on Al(111)

“…AgTe and AgSe display closed-packed atomic structures with a ( 3 × 3 ) structure. In addition, several metal monochalcogenide alloys show structures of chains, for example, Te on the Cu(111) system with ( 2 3 × 3 ) Cu–Te chains. − Recent angle-resolved photoemission spectroscopy (ARPES) measurements have reported that CuSe and AgTe possess two-dimensional Dirac nodal line fermions (its Dirac point extends along the M – Γ – K high symmetry line, forming the Dirac nodal line), protected by the mirror reflection symmetry. ,, Moreover, chalcogen-based surface alloys are also promising substrates for epitaxial growth. For example, the CDW properties of TiSe 2 could be tuned by CuSe substrates .…”