Electronic structure and morphology of thin surface alloy layers formed by deposition of Sn on Au(1 1 1)

Abstract

We demonstrate formation of thin AuSn and Au2Sn surface alloy layers at room and elevated substrate temperatures (TS = 413–493 K), respectively by the deposition of Sn on Au(1 1 1) using core-level X-ray photoelectron spectroscopy and scanning tunneling microscopy. Low energy electron diffraction patterns show different surface structures: p(3 × 3) R15° at room temperature for AuSn, 2113 at TS = 413 K and (3×3) R30° at TS = 493 K for Au2Sn. Angle resolved photoemission spectroscopy reveals evolution of bands from an electron-like surface state to appearance of a hole-like band structure corresponding to AuSn and Au2Sn. The 2113 phase of Au2Sn, which has a unit cell of oblique symmetry, exhibits an interesting linear band that meets at the Fermi level in the zone-center and have Fermi velocity comparable to graphene. Thus, our study establishes that Au-Sn bimetallic surface alloys have interesting electronic properties with potential for future applications.