problem,” says Patrick Vogt, The Quest a physicist at the Technical University of Berlin. He led a team of researchers from for 2-D France and Italy, who syn- thesized and investigated 5captionhed: 5caption starts with nested style 5captionhed. Silicon the properties of single lay- Image: Patrick Vogt ers of silicene and reported Silicene—the the results in April’s with silicene, Vogt, along claims in the April issue of silicon analogue to Physical Review Letters. with Guy LeLay from Journal of Physics: Condensed graphene—could The researchers created CINaM in Marseilles and Matter that its original work have amazing the monolayers by evaporat- Paolo De Padova from CNR- showed silicene as well. electronic abilities ing away silicon from a wafer ISM in Rome, resorted to Aufray even argues that the in a vacuum and allowing it an additional experimental layer obtained by Vogt and to carefully deposit on a sil- technique. They made STM his team might not be a real n 2004 two researchers, ver surface. Silicon and sil- observations of samples at silicon equivalent of gra- Andre Geim and Konstantin ver atoms do not form chem- different stages in the for- phene. “We think that sil- INovoselev, at the University ical bonds, so the silicon mation of the silicene layer. ver also plays a role as a cat- of Manchester, in England, atoms are forced to bond “We could see these sili- alyst and could force the announced the creation of with each other and settle cene islands grow, and we silicon atoms in specific graphene, a new, two-dimen- into a honeycomb structure, could measure the height of positions,” says Aufray. sional form of carbon with says Vogt. Unlike graphene, the forming layer,” he says. So the jury is still out unparalleled electronic which is perfectly planar, Just like graphene, sili- on whether anyone has properties. A decade ear- the silicene is corrugated. cene is expected to be a good truly created a silicon ana- lier, Kyozaburo Takeda and In 2010, other research- conductor, because electrons logue to graphene. And Kenji Shiraishi of NTT Basic ers claimed to have made can travel relatively long if they have, would it be Research Laboratories, in silicene. A group led by distances in it before they useful in electronics? Atsugi, Japan, predicted that Bernard Aufray at the scatter. However, critical Walter de Heer, who stud- a similar structure of silicon National Center for Scientific measurements of the elec- ies graphene at Georgia atoms—silicene—should exist. Research–Interdisciplinary tronic properties are not yet Tech, thinks it is unlikely, Now, a group of scientists in Nanoscience Center of possible. One of the prob- because silicene cannot exist Europe say they’ve finally Marseille, in France, found lems is that the silver sub- on its own without a sup- managed to create a sample of a silicene-like honeycomb strate on which silicene is port. “It deforms very eas- the stuff. Experts expect that structure in their scan- grown is itself a good con- ily and turns into a drop of silicene will have some of gra- ning tunneling micro- ductor. “This makes it very silicon,” he says. “As com- phene’s amazing abilities— scopic (STM) images difficult to understand what pared to graphene, sili- such as allowing electrons to following a similar evap- comes from the silver and cene is quite unstable.” speed through it as if they had oration experiment. what comes from the sili- However, some graphene no mass—but in an element But the interatomic dis- cene. If we had it on a semi- researchers are open to the more familiar to the semicon- tances they observed were conductor or an insulator, possibility. “Just because 3-D ductor industry. viewed by some scientists to that would be much eas- silicon is the most important Geim and Novoselev be too small to be ascribed ier,” says Vogt, who adds material available today, we had isolated graphene in an to silicene. And there was that aluminum nitride might shouldn’t jump to the con- embarrassingly simple man- another possible problem, be a possible substrate, an clusion that 2-D silicon will ner: They peeled it off graph- according to Vogt. “The silver idea he plans to investigate. be equally important,” says ite with Scotch tape. The cre- surface can mimic a honey­ For his part, Aufray Aravind Vijayaraghavan, a ation of a silicene layer was comb structure because intends to try to deposit sili- graphene researcher at the much more difficult. “There of its interaction with the cene on sodium chloride sur- University of Manchester. is no equivalent to graph- microscope,” he says. faces, which have a crystal- “On the other hand, it might ite where you could simply In order to prove that line structure close to that turn out to be even better!” peel it off, and that was the they were really dealing of silver. And his group —Alexander Hellemans

14 INT • iEEE Spectrum • july 2012 spectrum.ieee.org