Deposition of topological silicene, germanene and stanene on graphene-covered SiC substrates

Abstract

Growth of X-enes, such as silicene, germanene and stanene, requires passivated substrates to ensure the survival of their exotic properties. Using first-principles methods, we study as-grown graphene on polar SiC surfaces as suitable substrates. Trilayer combinations with coincidence lattices with large hexagonal unit cells allow for strain-free group-IV monolayers. In contrast to the Si-terminated SiC surface, van der Waals-bonded honeycomb X-ene/graphene bilayers on top of the C-terminated SiC substrate are stable. Folded band structures show Dirac cones of the overlayers with small gaps of about 0.1 eV in between. The topological invariants of the peeled-off X-ene/graphene bilayers indicate the presence of topological character and the existence of a quantum spin Hall phase.

Transport and Photoelectric Properties of 2D Silicene/MX2 (M = Mo, W; X = S, Se) Heterostructures

“…25−27 Several experimental groups have reported the epitaxial growth of SiE on metallic substrates such as MgX 2 (0001) (X = Cl, Br, I), 28,29 Ir(111), 30,31 Al(111), 32 and Ag(111), 33−42 and found, however, that the Dirac cone of SiE can be destroyed since the Si-π bands strongly hybridize with the substrates. 43−46 Many nonmetallic 2D materials as substrates, including graphite, 47 graphene, 48 silicon, 49,50 SiC, 51,52 PtSe 2 , 53 MoSi 2 , 54 and ZrC, 55 have also been proposed and investigated theoretically. Recently, high-buckled 2D Si nanosheets have been fabricated by molecular beam epitaxial growth on the bulk MoS 2 surface.…”

2D Elemental Nanomaterials Beyond Graphene

“…Atomically thin sheets of group‐III and post‐carbon group‐IV elements including B (borophene), Si (silicene), Ge (germanene) and Sn (stanene) have been synthesized on various substrates, but they have not been isolated as freestanding sheets due to the absence of their layered allotropes in Nature. It has been theoretically proposed that they are promising 2D topological insulators and high temperature superconductors …”

Towards topological quasifreestanding stanene via substrate engineering

“…On the basis of these observations, it is evident that any meaningful theoretical investigation must properly take the role of substrates into consideration. With a particular focus on stanene, several studies have attempted to include these effects [11,[16][17][18][19], while only a few of them have considered technologically achievable, and hence relevant, substrates [18,19]. Rather, our objective is to address commercial wafers of wide-gap semiconductors as possible substrate candidates, in order to follow the motif of reaching proposals that might allow for the integration of QSH physics into ambient life devices.…”