prof. Ing. Jan Čechal, Ph.D.
E-mail:   cechal@fme.vutbr.cz  Dept.:   Institute of Physical Engineering Position:   Associate Professor Room:   A3/421

Supervised courses:

• Bachelor Seminar (B-FIN) (TBS)
• Methods in Surface Science (DS133)
• Organic Nanostructures at Inorganic Surfaces (9ONA)
• Organic-inorganic interfaces (DS134)
• Selected Topics in Physics I (0KF)
• Selected Topics in Physics II (0FK)

Publications:

• STARÁ, V.; PROCHÁZKA, P.; MAREČEK, D.; ŠIKOLA, T.; ČECHAL, J.:
  Ambipolar remote graphene doping by low-energy electron beam irradiation
  journal article in Web of Science
• KORMOŠ, L.; PROCHÁZKA, P.; ŠIKOLA, T.; ČECHAL, J.:
  Molecular Passivation of Substrate Step Edges as Origin of Unusual Growth Behavior of 4,4′-Biphenyl Dicarboxylic Acid on Cu(001)
  journal article in Web of Science
• PROCHÁZKA, P.; MAREČEK, D.; LIŠKOVÁ, Z.; ČECHAL, J.; ŠIKOLA, T.:
  X-ray induced electrostatic graphene doping via defect charging in gate dielectric, NPG
  journal article in Web of Science
• ČECHAL, J.; KLEY, C.; PÉTUYA, R.; SCHRAMM, F.; RUBEN, M.; STEPANOW, S.; ARNAU, A.; KERN, K.:
  CO2 Binding and Induced Structural Collapse of a Surface-Supported Metal-Organic Network
  journal article in Web of Science
• PROCHÁZKA, P.; MACH, J.; BISCHOFF, D.; LIŠKOVÁ, Z.; DVOŘÁK, P.; VAŇATKA, M.; SIMONET, P.; VARLET, A.; HEMZAL, D.; PETRENEC, M.; KALINA, L.; BARTOŠÍK, M.; ENSSLIN, K.; VARGA, P.; ČECHAL, J.; ŠIKOLA, T.:
  Ultrasmooth metallic foils for growth of high quality graphene by chemical vapor deposition
  journal article in Web of Science
• KLEY, C.; ČECHAL, J.; KUMAGAI, T.; SCHRAMM, F.; RUBEN, M.; STEPANOW, S.; KERN, K.:
  Highly Adaptable Two-Dimensional Metal-Organic Coordination Networks on Metal Surfaces
  journal article in Web of Science

List of publications at Portal BUT

Abstracts of most important papers:

• ČECHAL, J.; POLČÁK, J.; ŠIKOLA, T.:
  Detachment Limited Kinetics of Gold Diffusion through Ultrathin Oxide Layers
  journal article in Web of Science
  Gold clusters and nanoparticles on ultrathin oxide layers are used as catalysts and represent essential parts of plasmonic and electronic devices. The stability of these nanostructures at surfaces against the diffusion of their constituents into the bulk is therefore of vital importance regarding their long-term applicability. Here, on the basis of in situ X-ray photoelectron spectroscopy measurements of gold diffusion through ultrathin oxide layers (SiO2 and Al2O3) to a Si substrate, we show that the diffusion from gold clusters/islands into the bulk is a detachment-limited process. Hence, the ultrathin oxide acts principally as a layer preventing a direct contact of metal atoms with the silicon substrate rather than a diffusion barrier. These findings contribute to a quantitative understanding of general design rules of metal/oxide structures.
• ČECHAL, J.; KLEY, C.; KUMAGAI, T.; SCHRAMM, F.; RUBEN, M.; STEPANOW, S.; KERN, K.:
  Convergent and divergent two-dimensional coordination networks formed through substrate-activated or quenched alkynyl ligation, Royal Society of Chemistry
  journal article in Web of Science
  Metal coordination assemblies of the symmetric bi-functional 4,4-di-(1,4-buta-1,3-diynyl)-benzoic acid are investigated by scanning tunnelling microscopy on metal surfaces. The formation of long-range ordered, short-range disordered and random phases depends on the competition between the convergent and divergent coordination motifs of the individual functional groups and is crucially influenced by the substrate.
• ČECHAL, J.; KLEY, C.; KUMAGAI, T.; SCHRAMM, F.; RUBEN, M.; STEPANOW, S.; KERN, K.:
  Functionalization of Open Two-Dimensional Metal–Organic Templates through the Selective Incorporation of Metal Atoms,
  Journal of Physical Chemistry C (print), Vol.117, (2013), No.17, pp.8871-8877, ISSN 1932-7447
  journal article - other
  Surface-confined molecular networks can serve as templates to steer the adsorption and organization of secondary ligands, metal atoms, and clusters. Here, the incorporation of Ni atoms and clusters into open two-dimensional robust metal–organic templates self-assembled from butadiyne dibenzoic acid molecules and Fe atoms on Au(111) and Ag(100) surfaces is investigated by scanning tunneling microscopy. The metal substrate plays a crucial role in the interaction of Ni atoms with the metal–organic host networks. On Ag(100) the metal–organic template steers the growth of Ni clusters underneath the network pattern near the central butadiyne moiety. In contrast, on Au(111) Ni interacts preferentially with the benzene rings forming size-limited clusters inside the network cavities. Thereby, on both surfaces Ni clusters consisting of a few atoms with both high areal density and thermal stability up to 450 K are realized. The Ni-functionalized networks enable the coordination of additional molecules into the open structures demonstrating the utilization of selective interactions for the assembly of multicomponent architectures at different organizational stages.
• ČECHAL, J.; TOMANEC, O.; ŠKODA, D.; KOŇÁKOVÁ, K.; HRNČÍŘ, T.; MACH, J.; KOLÍBAL, M.; ŠIKOLA, T.:
  Selective growth of Co islands on ion beam induced nucleation centers in a native SiO2 film,
  Journal of Aplied Physics, Vol.105, (2009), No.8, pp.084314-1-084314-6, ISSN 0021-8979
  journal article - other
  We present a straightforward method for fabrication of patterns of metallic nanostructures. The focused ion beam lithography (FIB) has been used to locally modify a native SiO2 layer on a silicon substrate. On the modified areas preferential nucleation of cobalt islands is observed. The cobalt islands formed upon deposition at 400 - 430 C combined with an intermediate annealing at 550 C have a uniform size distribution and their size can be controlled by the distance between the nucleation sites and the amount of deposited material. It is proposed that the island formation at patterned sites is due to reduced surface diffusion of Co atoms in the vicinity of FIB modified areas. The intermediate annealing improves the island morphology since the kinetic diffusion limits are lowered and system reconfigures towards its equilibrium state.
• ČECHAL, J.; KOLÍBAL, M.; KOSTELNÍK, P.; ŠIKOLA, T.:
  Gallium structure on the Si(111)-(7 x 7) surface: influence of Ga coverage and temperature,
  Journal of Physics: Condensed Matter, Vol.19, (2007), No.1, pp.016011-16025, ISSN 0953-8984
  journal article - other
  The results of gallium deposition on the Si(111)-(7 x 7) surface at different substrate temperatures (-183, RT, 300, 490 and 530 C) as well as the influence of subsequent annealing of the prepared layers are presented. The gallium structure was monitored by low-energy electron diffraction (LEED) and synchrotron radiation photoelectron spectroscopy (SR-PES). A detailed analysis of photoelectron spectra was carried out and three different Ga 3d peak components recognized.the first one was related to the (R3xR3) R30 reconstruction, the second to gallium island bases, and the third one to metallic gallium deposited on these bases. Depending on substrate temperature either only the island bases were formed (over 490 C) or these bases were covered with extra gallium atoms in an additional layer (300 C). In the case of room (low) temperature deposition only a weak interaction of gallium with the (7x7) substrate and a non-ordered growth were found. If the gallium coverage exceeded a critical value the gallium formed small droplets on the silicon surface. Annealing of the deposited layers showed differences between the second and the third gallium layer. In addition to previously reported structures a new (3R3x3r3) R30 reconstruction was observed after high temperature deposition followed by annealing to 530 C. This structure was stable in a narrow temperature range and forms an ntermediate step between the (R3 x R3) R30 reconstruction and the island structure.