Mobility of ionic hydrates
Jun/18 paper in Nature about mobility of ionic hydrates studied by high-resolution AFM. »more info

O. Wichterle prize
Jun/18 O. Stetsovych received O. Wichterle prize for outstanding young scientists at the AS CR. »more info

Piezoelectricity of single molecules
Jan/18 paper in JACS demonstrating piezoelectric effect on single molecules »more info

Resolving water clusters with AFM
Jan/18 paper in Nature Comm. about a method allowing high-resolution AFM of weakly coupled clusters »more info

High-resolution SPM imaging
Sep/17 paper in PRL reporting AFM/STM/IETS imaging »more info

Electronegativity of atoms
May/17 paper in Nature Comm. »more info

Transfer of chirality
Feb/17 Paper published in Nature Chemistry including News&Views. »more info

Towards chemical recognition of molecules
Aug/16 Paper published in ACS Nano. »more info

Odehnal award
June/16 O. Stetsovych received Odehnal award »more info

Praemium Academiae
June/16 P. Jelinek received CAS award »more info

Imaging electrostatic field
May/16 paper in Nature Comm. »more info

O. Wichterle prize
May/16 P. Hapala received O. Wichterle prize for outstanding young scientists at the AS CR. »more info

On-surface chemical synthesis
Apr/16 paper in JACS »more info

Structural and Electronic Properties of Nitrogen-Doped Graphene
Mar/16 Paper in Phys. Rev. Lett. »more info

Role of the electrostatic force in AFM images
Mar/16 Paper in Phys. Rev. Lett »more info

Charge transport between two molecules
Sep/15 Paper in Phys. Rev. Lett »more info

The best poster ECOSS-31
Sep/15 Our work has been selected as the best poster in the ECOSS-31 conference. »more info

Paper in ACS Nano
Aug/15 Novel way of B,N-co doping of graphene demonstrated. »more info

paper in PRL and Physics
Aug/15 Our work has been published in Phys. Rev. Lett highlighted as Synopsis in Physics. »more info

Paper in Nature Comm.
Jul/15 High-resolution AFM images reported at room temperature. »more info

Paper in Nano Letters
Jun/15 The current and the force used for controlled atomic switching of silicon tetramer. »more info

O. Wichterle prize
May/15 M. Ondracek received O. Wichterle prize for outstanding young scientists at the AS CR. »more info

No way of Silicene

We performed an extensive experimental and theoretical analysis using many techiques, which shows unambiguously that formation of silicine on noble metals such as Pt(111) or Ir (111) is very unlikely. Instead we define a model of ordered 2D surface alloy, which meets all experimental evidences obtained by different surface science techniques and the state- of the art calculations.

Silicene, the silicon-based counterpart of graphene, is probably the most desired 2D material for nanoelectronic industry these days. This dream initiated an extensive search for a recipe how to grow the silicene. Many research groups, encouraged by pioneering works reporting growth of silicene 2D sheets on Ag surfaces, have directed their attention to other noble metal surfaces. Recently, several papers reported formation of silicene on Ir or Pt surfaces based on a simple comparison of experimental evidence of LEED, STM to DFT and STM calculations.

On the other hand, for many years it is well known that Si forms binary alloys with the majority of the transition metals. It is known as well, that by tuning the particular thermodynamical conditions, Si can segregate to the surface of some metals, forming surface alloys. Nevertheless a detailed knowledge of atomic and electronic structure of such surface alloys is still missing. Partly it was due to a limited set of atomic resolution images, but also due to a lack of other experimental data together with a thorough analysis, that would allow the atomic structure determination; e.g. LEED-IV patterns, ARUPS.

In order to resolve the “silicene vs. surface alloy” problem and to understand precisely the atomic structure of the real surface phases, we provided an extensive comparison of the experimental data with different atomistic models including silicene. We used a set of complementary experimental techniques supported by the state-of-the-art theoretical analysis. Namely we present detailed investigation of the atomic and electronic structure of Si-(19x19)R23.4°/Pt(111) surface reconstruction by means of STM, nc-AFM, SRPES, LEED-IV and ARUPS, ; supported by theoretical calculations - DFT, STM simulation, IV-LEED simulation and k-space electronic band projection. We proposed an atomistic model consisting of ordered Si/Pt surface alloy, which fits very well to experimental evidence collected by all employed techniques. To make our conclusions more relevant, we extended our consideration to similar system - the Si-()R19.1°/Ir(111). Also here our surface alloy model made of characteristic metal/Si tetramers is thermodynamically more favorable than a silicene 2D sheet grown on top of Ir(111) surface. These findings indicate generality of our model and they render unlikely any formation of silicene or germanene on Pt(111) and some other transition metal surfaces such as Ir(111).

Fig. Schematic view of the proposed model of Si-Pt surface alloy forming Kagome lattice and comparions of experimental and calculated STM images.