科研之友
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摘要
Silicene is a two-dimensional material with a Dirac-type band structure and it is particularly attractive due to its potential for integration with Si-based technology. The primary focus has been to grow single silicene layers and understand how the electronic structure is affected by the substrate and the phase transition between low- and high-budding configurations. Typically, silicene is synthesized by depositing, monolayer amounts of silicon,Onto a heated Ag(111) surface; however, other growth substrates such as Ir(111) and ZrB2 have been studied recently. We present a novel route for silicene synthesis via a high temperature surface reconstruction of hexagonal-MoSi2 nanocrystallites. The h-MoSi2 crystallites are formed by annealing of thin Mo-layers on Si(100)-(2 x 1) and their crystallographic orientation is controlled via an epitaxial relation with :the Si-substrate. The (0001) plane of h-MoSi2 is comprised of Si-hexagons with a Mo atom residing in the center. Annealing above approximately 650 degrees C causes the (0001) plane to undergo a surface reconstruction process leaving a honeycomb pattern on the surface of these crystallites as' shown by scanning tunneling microscopy. We define this surface layer as a silicene-like reconstruction (SLR), and a detailed geometric analysis of our structure yields a perfect match with the (root 3 x root 3)R30 degrees silicene superstructure in a low-buckled configuration (ABA). Scanning tunneling spectroscopy data of the SLR, Si(001)-(2 x 1) and h-MoSi2 surfaces agree with this interpretation. The formation of this structure on a transition metal silicide opens up the opportunity for integration into Si based devices without the necessity for a transfer scheme.
- 出版日期2017-1
