Epitaxial growth of two-dimensional stanene

Abstract

Following the first experimental realization of graphene, other ultrathin materials with unprecedented electronic properties have been explored, with particular attention given to the heavy group-IV elements Si, Ge and Sn. Two-dimensional buckled Si-based silicene has been recently realized by molecular beam epitaxy growth, whereas Ge-based germanene was obtained by molecular beam epitaxy and mechanical exfoliation. However, the synthesis of Sn-based stanene has proved challenging so far. Here, we report the successful fabrication of 2D stanene by molecular beam epitaxy, confirmed by atomic and electronic characterization using scanning tunnelling microscopy and angle-resolved photoemission spectroscopy, in combination with first-principles calculations. The synthesis of stanene and its derivatives will stimulate further experimental investigation of their theoretically predicted properties, such as a 2D topological insulating behaviour with a very large bandgap, and the capability to support enhanced thermoelectric performance, topological superconductivity and the near-room-temperature quantum anomalous Hall effect.

Large-gap quantum spin Hall states in decorated stanene grown on a substrate

“…Recently, monolayer stanene has been successfully fabricated by molecular beam epitaxy (MBE) on Bi 2 Te 3 (111) substrate [24], which, for the first time, established the existence of the theoretically predicted stanene structure. Unfortunately, valence bands of stanene are pinned with conduction bands of Bi 2 Te 3 (111), giving metallic interface states [24]. When growing stanene on a different substrate, the binding configuration and bonding strength vary, and the charge redistribution and energy level alignment at the interface also differ.…”

“…This feature together with the out-of-plane orientation of the p z orbital facilitate strong orbital interaction with external environments. Therefore, electronic properties of bare stanene are easily affected by adsorbates and substrate [24]. The disadvantage may be overcome by passivating the p z orbital.…”

Intrinsic Charge Transport in Stanene: Roles of Bucklings and Electron–Phonon Couplings

“…[10] The experimental buckling value of stanene on Bi 2 Te 3 substrate was found to be 1.2 ± 0.2 Å, which was ascribed to strain-induced enhancement effect. [11] The unit cell of stanene consists of two sublattices and the reciprocal space is shown in Figure 1b with the first Brillouin zone and the high symmetry points Γ = (0, 0), K= (1/3, 1/3), K′ = (2/3, -1/3), and M = (1/2, 0) whose base is spanned by b 1 and b 2 . The Dirac cones are seen at k = K and k = K′, which we will denote as Dirac point K and K′, respectively.…”

“…[5] The group IV elemental analogues of graphene, including silicene, [6] germanene, [7] and stanene, [8][9][10][11] are promising alternatives going beyond graphene owing to their outstanding electronic properties. Molecular beam epitaxy technique facilitates the materials fabrications.…”

“…Molecular beam epitaxy technique facilitates the materials fabrications. [6,7,11] Among these group IV elemental 2D sheets, stanene draws particular attention since it has been predicted to be a topological insulator with large band gap theoretically, [12][13][14][15] arousing interests in dissipationless electronics. Moreover, stanene also shows enhanced thermoelectric performance, [16,17] near-room-temperature quantum anomalous effect, [18] and topological superconductivity.…”