![]() Growth of silicon was also demonstrated on graphite, a van der Waals material, with the idea to suppress the interaction with the substrate and as such to preserve the Dirac properties. Although a linear dispersion relation has been observed, it is argued by others that this band is related to the Ag substrate rather than to silicene or to combined effects of silicene and the Ag(111) substrate. Unfortunately, due to the strong coupling between Si ad-layer and Ag substrate, the interesting Dirac properties of silicene are destroyed. Several studies have reported on the growth of a 2D silicon layer on Ag(111). Silicene does not occur in nature and therefore it has to be synthesized. Another attractive property of silicene is its spin–orbit coupling, which is substantially larger than the spin–orbit coupling in graphene. This band gap makes silicene a very appealing candidate for field-effect-based devices. The broken sub-lattice symmetry of silicene allows for the opening of a band gap in this material. Similar to graphene, the electrons near the Fermi level in free-standing silicene are predicted to behave as massless Dirac fermions. found that germanene also exhibits similar properties as graphene and silicene. Interestingly, the linear dispersing energy bands at the K points, the so-called Dirac cones, are robust against the buckling of the silicene lattice. Inspired by this analogy they put forward the name silicene for the two-dimensional silicon. They pointed out that the graphite-like silicon sheet has linearly dispersing energy bands near the K points of the Brillouin zone, very comparable to graphene. In 2007, Guzmán-Verri and Lew Yan Voon performed tight-binding calculations of two-dimensional silicon. In addition, the calculations of Takeda and Shiraishi also revealed that silicene and germanene are semi-metals, like graphene. These authors pointed out that two-dimensional silicon and germanium are not planar but buckled, i.e., the two sub-lattices of the honeycomb lattice are displaced with respect to each other in a direction normal to the two-dimensional sheet. The first calculations of graphite-like allotropes of silicon and germanium were performed by Takeda and Shiraishi in 1994. One appealing candidate is silicene, a graphene-like 2D allotrope of silicon. Since the discovery of graphene interest has extended to the search for other 2D materials with properties similar to graphene. Finally, density functional theory calculations indicate that silicene clusters encapsulated by MoS 2 are stable. 2014, 26, 2096–2101) that silicon forms a highly strained epitaxial layer on MoS 2. Our conclusion that Si intercalates upon the deposition on MoS 2 is at variance with the interpretation by Chiappe et al. Based on these experimental observations we have to conclude that deposited Si atoms do not reside on the MoS 2 surface, but rather intercalate between the MoS 2 layers. (5) X-ray photo-electron spectroscopy measurements reveal that sputtering of the MoS 2/Si substrate does not lead to a decrease, but an increase of the relative Si signal. (4) Spatial maps of d I/d z reveal that the surface exhibits a uniform work function and a lattice constant of 3.16 Å. (3) I( V) scanning tunneling spectroscopy spectra recorded at the hills and valleys reveal no noteworthy differences. (2) The transitions from hills to valleys are not abrupt, as one would expect for epitaxial islands growing on-top of a substrate, but very gradual. The lattice constant of the hill-and-valley structure amounts to 3.16 Å, which is exactly the lattice constant of pristine MoS 2. Our evidence relies on several experimental observations: (1) Upon the deposition of Si on pristine MoS 2 the morphology of the surface transforms from a smooth surface to a hill-and-valley surface. At room temperature and low deposition rates we have found compelling evidence that the deposited Si atoms intercalate between the MoS 2 layers. We report a combined experimental and theoretical study of the growth of sub-monolayer amounts of silicon (Si) on molybdenum disulfide (MoS 2). ![]()
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