Atomic and Electronic Structures of Unreconstructed Polar MgO(111) Thin Film on Ag(111)

TL;DR

This study investigates the atomic and electronic properties of a flat, unreconstructed polar MgO(111) thin film grown on Ag(111), revealing its semiconducting or metallic nature rather than insulating behavior.

Contribution

It demonstrates the successful growth of a stable, unreconstructed MgO(111) surface and analyzes its electronic structure using multiple spectroscopic techniques.

Findings

MgO(111) film is flat and unreconstructed

Surface exhibits finite density of states at Fermi level

Surface is semiconducting or metallic, not insulating

Abstract

Atomic and electronic structures of a polar surface of MgO formed on Ag(111) was investigated by using reflection high energy electron diffraction (RHEED), Auger electron spectroscopy, electron energy loss spectroscopy (EELS), and ultraviolet photoemission spectroscopy (UPS). A rather flat unreconstructed polar MgO(111) 1$\times$1 surface could be grown by alternate adsorption of Mg and O$_{2}$ on Ag(111). The stability of the MgO(111) surface was discussed in terms of interaction between Ag and Mg atoms at the interface, and charge state of the surface atoms. EELS of this surface did not show a band gap region, and finite density of states appeared at the Fermi level in UPS. These results suggest that a polar MgO(111) surface was not an insulating surface but a semiconducting or metallic surface.