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March 30, 2012

Single molecular thick silicon - silicene claims and research

Inside Science - Several research groups claim to have thin one molecule thick sheets of silicon called silicene (analogous to graphene for carbon), igniting a controversy over who won the race to synthesize this promising new material. According to Lew Yan Voon, electronic devices based on silicene could reliably exhibit the critical on-off function required for transistors, the building blocks of computers. Graphene, however, has struggled to achieve this function, stymieing its practical use as a transistor.

Despite the uncertainty over who created silicene first, researchers agree what needs to be done next. To take full advantage of silicene's properties, physicists need to grow it on an insulating material that won't conduct electricity like silver. Once silicene can be grown on an insulator, it will be much easier to develop silicene transistors and other devices.

Scientists may develop silicene devices that dramatically increase processing speed relatively soon, but large challenges remain, according to Le Lay.

"From this to applications is another big step. It's not trivial," said Le Lay.

Some Interesting Silicene Research

Physical review letters - Silicene: Compelling experimental evidence for graphenelike two-dimensional silicon (2012)

Due to its unique physical properties graphene, a 2D honeycomb arrangement of carbon atoms, has attracted tremendous attention. Silicene, the graphene equivalent for silicon, could follow this trend, opening new perspectives for applications, especially due to its compatibility with Si-based electronics. Silicene has been theoretically predicted as a buckled honeycomb arrangement of Si-atoms and an electronic dispersion resembling that of relativistic Dirac fermions. Here we provide compelling evidences, from both structural and electronic properties, for the synthesis of epitaxial silicene sheets on a silver (111) substrate, through the combination of scanning tunneling microscopy and angular-resolved photoemission spectroscopy in conjunction with calculations based on density functional theory.

Applied Physics Letters - Epitaxial growth of a silicene sheet (2010)




Computer Physics Communications - Structural stability of silicene-like nanotubes

Silicene-like (4,0) zigzag metal-doped MSi nanotubes are investigated by first-principles calculations. We show that the geometrical structures of silicon nanotubes can be stabilized by doping metal (K, Ca, Y and Lu). Electronic structure calculations show that Y and Lu atoms gain extra charge from Si atoms, the bonding between Si and the MSi (M = K, Ca) is of a mixed metallic-covalent nature, and the magnetic moment of K14Si120 quenches completely compared with K7Si64. Some properties are discussed to provide guidance to experimental efforts for nanomagnetic materials and spintronics.

Physical Review B - Electrically tunable band gap in silicene

We report calculations of the electronic structure of silicene and the stability of its weakly buckled honeycomb lattice in an external electric field oriented perpendicular to the monolayer of Si atoms. The electric field produces a tunable band gap in the Dirac-type electronic spectrum, the gap being suppressed by a factor of about eight by the high polarizability of the system. At low electric fields, the interplay between this tunable band gap, which is specific to electrons on a honeycomb lattice, and the Kane-Mele spin-orbit coupling induces a transition from a topological to a band insulator, whereas at much higher electric fields silicene becomes a semimetal.

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