Free-standing silicene, a silicon analogue of graphene, has a buckled honeycomb lattice and, because of its Dirac bandstructure combined with its sensitive surface, offers the potential for a widely tunable two-dimensional monolayer, where external fields and interface interactions can be exploited to influence fundamental properties such as bandgap and band character for future nanoelectronic devices. The quantum spin Hall effect, chiral superconductivity, giant magnetoresistance and various exotic field-dependent states have been predicted in monolayer silicene. Despite recent progress regarding the epitaxial synthesis of silicene and investigation of its electronic properties, to date there has been no report of experimental silicene devices because of its air stability issue. Here, we report a silicene field-effect transistor, corroborating theoretical expectations regarding its ambipolar Dirac charge transport, with a measured room-temperature mobility of ∼100 cm(2) V(-1) s(-1) attributed to acoustic phonon-limited transport and grain boundary scattering. These results are enabled by a growth-transfer-fabrication process that we have devised--silicene encapsulated delamination with native electrodes. This approach addresses a major challenge for material preservation of silicene during transfer and device fabrication and is applicable to other air-sensitive two-dimensional materials such as germanene and phosphorene. Silicene's allotropic affinity with bulk silicon and its low-temperature synthesis compared with graphene or alternative two-dimensional semiconductors suggest a more direct integration with ubiquitous semiconductor technology.

The structural and electronic properties of silicene nanosheets epitaxially grown on Ag(111) are systematically investigated by combining scanning tunneling microscopy and scanning tunneling spectroscopy. By carefully tuning the growth parameters, complex 2D silicon structures are obtained, which evidence the presence of corrugated silicene domains. Local modifications of the density of states are observed throughout reconstructed silicene domains and are attributed to the symmetry breaking induced by the interactions with the Ag lattice, in analogy with the case of graphene.

The structural and electronic properties of a Si nanosheet (NS) grown onto a MoS2 substrate by means of molecular beam epitaxy are assessed. Epitaxially grown Si is shown to adapt to the trigonal prismatic surface lattice of MoS2 by forming two-dimensional nanodomains. The Si layer structure is distinguished from the underlying MoS2 surface structure. The local electronic properties of the Si nanosheet are dictated by the atomistic arrangement of the layer and unlike the MoS2 hosting substrate they are qualified by a gap-less density of states.

The chemical stability of buckled silicene, i.e., the silicon counterpart of graphene, is investigated then resulting in a low reactivity with O 2 when dosing up to 1000 L and in a progressive oxidation under ambient conditions. The latter drawback is addressed by engineering ad hoc Al-and Al 2 O 3 -based encapsulations of the silicene layer. This encapsulation design can be generally applied to any silicene confi guration, irrespective of the support substrate, and it leads to the fabrication of atomically sharp and chemically intact Al/silicene and Al 2 O 3 /silicene interfaces that can be functionally used for ex situ characterization as well as for gated device fabrication.

By combining experimental techniques with ab-initio density functional theory calculations, we describe the Si/Ag(111) two-dimensional system in terms of a sp 2 -sp 3 crystalline form of silicon characterized by a vertically distorted honeycomb lattice. We show that 2D sp 2 -sp 3 Si NSs are qualified by a prevailing Raman peak which can be assigned to a graphene-like E 2g vibrational mode and that highly distorted superstructures are semiconductive whereas low distorted ones behave as semimetals.