Kyushu University Academic Staff Educational and Research Activities Database
List of Papers
ANTON VISIKOVSKIY Last modified date:2021.06.23

Assistant Professor / Applied Physics / Department of Applied Quantum Physics and Nuclear Engineering / Faculty of Engineering

1. Iimori Takushi, Visikovskiy Anton, Imamura Hitoshi, Miyamachi Toshio, Kitamura Miho, Horiba Koji, Kumigashira Hiroshi, Mase, Kazuhiko, Nakatsuji Kan, Tanaka Satoru, Komori, Fumio, Electronic structure of 3 degrees-twisted bilayer graphene on 4H-SiC(0001), PHYSICAL REVIEW MATERIALS, 10.1103/PhysRevMaterials.5.L051001, 5, 5, L051001, 2021.05, [URL], The electronic structure of 3 degrees-twisted bilayer graphene (TBG) is studied by angle-resolved photoelectron spectroscopy (ARPES). Sub-mm-sized TBG prepared by direct bonding in a high vacuum enabled us to use conventional ARPES band mapping with synchrotron light. The results indicate that strong interlayer coupling makes a moire potential for the Dirac electrons and significantly modifies the graphene bands around the (K) over bar points such as the band splitting and electron velocity reduction. The observed electronic structure is consistently reproduced by tight-binding calculations combined with a band unfolding method..
2. H. Imamura, A. Visikovskiy, R. Uotani, T.Kajiwara, H. Ando, T. Iimori, K. Iwata, T. Miyamachi, K. Nakatsuji, K. Mase, T. Shirasawa, F. Komori, S. Tanaka, Twisted bilayer graphene fabricated by direct bonding in a high vacuum, APPLIED PHYSICS EXPRESS, 10.35848/1882-0786/ab99d1, 13, 7, 075004, 2020.07.
3. H. Ando, A. Visikovskiy, T. Nakagawa, S. Mizuno, S.Tanaka, Structure determination of hydrogen-terminated 4H-SiC(0001) by LEED, PHYSICAL REVIEW B, 10.1103/PhysRevB.99.235434, 99, 23, 235434, 2019.06, [URL], SiC(0001)-(1 x 1)-H consisting of monohydride is a preferred starting surface structure for synthesis of the two-dimensional materials on SiC(0001). Here we report preparation of the SiC(0001)-(1 x 1)-H by atomic hydrogen exposure and structure determination of the SiC(0001)-(1 x 1)-H by a quantitative LEED analysis. Our data show that the SiC(0001)-(1 x 1)-H is indeed a bulk terminated unreconstructed SiC(0001) surface. The sample morphology was also investigated using AFM. The dominance of one of two possible inequivalent surface terminations of 4H polytype of SiC crystal was confirmed..
4. Koichiro Yaji, Anton Visikovskiy, Takushi Iimori, Kenta Kuroda, Singo Hayashi, Takashi Kajiwara, Tanaka Satoru, Fumio Komori, Shik Shin, Coexistence of Two Types of Spin Splitting Originating from Different Symmetries, Physical Review Letters, 10.1103/PhysRevLett.122.126403, 122, 12, 126403, 2019.03, The symmetry of a surface or interface plays an important role in determining the spin splitting and texture of a two-dimensional band. Spin-polarized bands of a triangular lattice atomic layer (TLAL) consisting of Sn on a SiC(0001) substrate is investigated by spin- and angle-resolved photoelectron spectroscopy. Surprisingly, both Zeeman- and Rashba-type spin-split bands, without and with spin degeneracy, respectively, coexist at a K point of the Sn TLAL. The K point has a threefold symmetry without inversion symmetry according to the crystal structure including the SiC periodicity, meaning that the Zeeman-type is consistent with the symmetry of the lattice while the Rashba-type is inconsistent. Our density functional calculations reveal that the charge density distribution of the Rashba-type (Zeeman-type) band shows (no) inversion symmetry at the K point. Therefore, the symmetry of the charge density distribution agrees with both types of the spin splitting..
5. Shingo Hayashi, Anton Visikovskiy, Takashi Kajiwara, Takushi Iimori, Tetsuroh Shirasawa, Kan Nakastuji, Toshio Miyamachi, Shuhei Nakashima, Koichiro Yaji, Kazuhiko Mase, Fumio Komori, Tanaka Satoru, Triangular lattice atomic layer of Sn(1 × 1) at graphene/SiC(0001) interface, Applied Physics Express, 10.7567/APEX.11.015202, 11, 1, 2018.01, Sn atomic layers attract considerable interest owing to their spin-related physical properties caused by their strong spin-orbit interactions. We performed Sn intercalation into the graphene/SiC(0001) interface and found a new type of Sn atomic layer. Sn atoms occupy on-top sites of Si-terminated SiC(0001) with in-plane Sn-Sn bondings, resulting in a triangular lattice. Angle-resolved photoemission spectroscopy revealed characteristic dispersions at and points, which agreed well with density functional theory calculations. The Sn triangular lattice atomic layer at the interface showed no oxidation upon exposure to air, which is useful for characterization and device fabrication ex situ..
6. Koichiro Ienaga, Takushi Iimori, Koichiro Yaji, Toshio Miyamachi, Shuhei Nakashima, Yukio Takahashi, Kohei Fukuma, Shingo Hayashi, Takashi Kajiwara, Anton Visikovskiy, Kazuhiko Mase, Kan Nakatsuji, Tanaka Satoru, Fumio Komori, Modulation of Electron-Phonon Coupling in One-Dimensionally Nanorippled Graphene on a Macrofacet of 6H-SiC, Nano Letters, 10.1021/acs.nanolett.7b00606, 17, 6, 3527-3532, 2017.06, Local electron-phonon coupling of a one-dimensionally nanorippled graphene is studied on a SiC(0001) vicinal substrate. We have characterized local atomic and electronic structures of a periodically nanorippled graphene (3.4 nm period) prepared on a macrofacet of the 6H-SiC crystal using scanning tunneling microscopy/spectroscopy (STM/STS) and angle-resolved photoelectron spectroscopy (ARPES). The rippled graphene on the macrofacets distributes homogeneously over the 6H-SiC substrate in a millimeter scale, and thus replica bands are detected by the macroscopic ARPES. The STM/STS results indicate the strength of electron-phonon coupling to the out-of-plane phonon at the K̄ points of graphene is periodically modified in accordance with the ripple structure. We propose an interface carbon nanostructure with graphene nanoribbons between the surface rippled graphene and the substrate SiC that periodically modifies the electron-phonon coupling in the surface graphene..
7. ANTON VISIKOVSKIY, Takashi KAJIWARA, Masamichi Yoshimura, Takushi IIMORI, Fumio KOMORI, 田中 悟, Graphene/SiC(0001) interface structures induced by Si intercalation and their influence on electronic properties of graphene, PHYSICAL REVIEW B, 10.1103/PhysRevB.94.245421, 94, 24, 245421, 2016.12, [URL], Epitaxial graphene growth on SiC surfaces is considered advantageous in terms of device application. However, the first graphitic layer on SiC transforms to a buffer layer because of strong coupling with the substrate. The properties of several subsequent layers are also significantly degraded. One method to decouple graphene from the substrate is Si intercalation. In the present work, we report observation and analysis of interface structures formed by Si intercalation in between the graphene layer and the SiC(0001) surface depending on Si coverage and influence of these interfaces on graphene electronic structure by means of low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), angle-resolved photoemission spectroscopy (ARPES), and theoretical first-principles calculations. The STM appearance of observed periodic interface structures strongly resembles previously known Si-rich phases on the SiC(0001) surface. Based on the observed range of interface structures we discuss the mechanism of graphene layer decoupling and differences in stability of the Si-rich phases on clean SiC(0001) and in the graphene/SiC(0001) interface region. We also discuss a possibility to tune graphene electronic properties by interface engineering..
8. ANTON VISIKOVSKIY, K. Mitsuhara, Y. Kido, Role of gold nanoclusters supported on TiO2(110) model catalyst in CO oxidation reaction, JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A, 10.1116/1.4825117, 31, 6, 061404, 2013.11, [URL], It was reported previously that O adatoms adsorbed dissociatively on the five-fold Ti rows of rutile TiO2(110) made the surface O-rich and reacted with CO molecules to form CO2. An electronic charge transfer taking place from gold nanoclusters to the O-rich TiO2(110) support played a crucial role to enhance the catalytic activity [Mitsuhara et al., J. Chem. Phys. 136, 124303 (2012)]. In this study, the authors have further accumulated experimental data for the CO oxidation reaction enhanced by gold nanoclusters on the TiO2(110) surface. Based on the results obtained here and previously, the authors propose an "interface dipole model," which explains the strong activity of Au nanoclusters supported on O-rich TiO2(110) in CO oxidation reaction. Simultaneously, the authors also discuss the cationic cluster model proposed by Wang and Hammer [Phys. Rev. Lett. 97, 136107 (2006)] and the d-band model predicted by Hammer and Norskov [Adv. Catal. 45, 71 (2000)]. The latter is, in particular, widely accepted to explain the activities of heterogeneous catalysts. Contrary to the d-band model, our ab initio calculations demonstrate that the d-band center for Au nanoclusters moves apart from the Fermi level with decreasing the cluster size and this is due to contraction of the Au-Au bond length..
9. ANTON VISIKOVSKIY, K. Mitsuhara, M. Hazama, M. Kohyama, Y. Kido, The atomic and electronic structures of NiO(001)/Au(001) interfaces, JOURNAL OF CHEMICAL PHYSICS, 10.1063/1.4820823, 139, 14, 144705, 2013.10, [URL], The atomic and electronic structures of NiO(001)/Au(001) interfaces were analyzed by high-resolution medium energy ion scattering (MEIS) and photoelectron spectroscopy using synchrotronradiation-light. The MEIS analysis clearly showed that O atoms were located above Au atoms at the interface and the inter-planar distance of NiO(001)/Au(001) was derived to be 2.30 +/- 0.05 angstrom, which was consistent with the calculations based on the density functional theory (DFT). We measured the valence band spectra and found metallic features for the NiO thickness up to 3 monolayer (ML). Relevant to the metallic features, electron energy loss analysis revealed that the bandgap for NiO(001)/Au(001) reduced with decreasing the NiO thickness from 10 down to 5 ML. We also observed Au 4f lines consisting of surface, bulk, and interface components and found a significant electronic charge transfer from Au(001) to NiO(001). The present DFT calculations demonstrated the presence of an image charge beneath Ni atoms at the interface just like alkali-halide/metal interface, which may be a key issue to explain the core level shift and band structure..
10. Yoshihito Hagihara, Takashi Kajiwara, ANTON VISIKOVSKIY, Tanaka Satoru, Graphene Nanoribbons Grown on Epitaxial SixCyOz Layer on Vicinal SiC(0001) Surfaces by Chemical Vapor Deposition, APPLIED PHYSICS EXPRESS, 10.7567/APEX.6.055102, 6, 5, 055102, 2013.05, [URL], Graphene nanoribbons (GNRs) were grown on n-type vicinal 6H-SiC substrates as a template, consisting of periodic nanosurface, by chemical vapor deposition (CVD). Selective growth was achieved and resulted in narrow (5-10 nm width) and millimeter-long GNRs. The GNRs contained randomly rotated domains, however, initial nuclei indicated single domain features, possibly aligned to step edges. The resistivity measurement on GNRs grown on semi-insulating SiC substrate indicated transport properties only along GNRs but no current flow across GNRs, indicating growth of electrically isolated bunches of GNRs..
11. Takashi Kajiwara, Yuzuru Nakamori, ANTON VISIKOVSKIY, Takushi Iimori, Fumio Komori, Kan Nakatsuji, Kazuhiko Mase, Tanaka Satoru, Graphene nanoribbons on vicinal SiC surfaces by molecular beam epitaxy, American Physical Society, 10.1103/PhysRevB.87.121407, 87, 12, 121407, 2013.03, [URL].
12. T. Matsuda, M.Tagami, Kei Mitsuhara, ANTON VISIKOVSKIY, M. Shibuya, Yoshiaki Kido, 3C-SiC(001)-3 x 2 reconstructed surface analyzed by high-resolution medium energy ion scattering, SURFACE SCIENCE, 10.1016/j.susc.2012.08.021, 606, 23-24, 1942-1947, 2012.12, [URL].
13. Tomoaki Nishimura, Kei Mitsuhara, ANTON VISIKOVSKIY, Yoshiaki Kido, Cross sections for medium energy He ions scattered from Hf and Au atoms, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS, 10.1016/j.nimb.2012.02.030, 280, 5, 2012.06, [URL], The elastic scattering cross sections for medium energy He ions incident on Ni, Hf and Au atoms were measured precisely using a toroidal electrostatic analyzer. We prepared the targets of Ni(similar to 1 nm)/HfO2(1.5 nm)/Si(001) and Ni(similar to 1 nm)/Au(similar to 0.5 nm)/Si(111) and performed in situ ion scattering measurement under ultrahigh vacuum condition. The absolute amounts of Ni, Hf and Au were determined by Rutherford backscattering using 1.5 MeV He ions at a scattering angle of 150 degrees. The scattering cross sections for Hf and Au were normalized by those for Ni to avoid the ambiguities of the number of incident particles, solid angle subtended by a detector, detection efficiency and the He fractions for the emerging He ions from the surfaces. The results obtained are compared with the simple Lee-Hart formula and the calculated values using the Moliere and ZBL potentials and the potentials derived from the Hartree-Fock-Slater wave functions. .
14. Kei Mitsuhara, H. Okumira, T. Matsuda, M. Tagami, ANTON VISIKOVSKIY, Yoshiaki Kido, Detection of H+ recoiled from Si(111)-1 x 1-H by medium energy Ne+ impact, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS, 10.1016/j.nimb.2012.01.035, 276, 56, 2012.04, [URL], We detected the H+ ions recoiled from Si(111)-1 x 1-H by medium energy 80-150 keV Ne+ impacts. The H+ fraction is dependent on emerging angle and emerging energy. With decreasing the emerging angle scaled from the surface normal the H+ fraction increases and reaches a saturation below similar to 70 degrees and almost 100% for emerging energy above 13 keV. In contrast, the charge state is not equilibrated even at similar to 85 degrees. Such strong dependence on emerging angle is due to the location of H bound by Si atoms on top of the surface. The sensitivity to H on the surfaces is estimated to be better than 5 x 10^12 atoms/cm^2 at a small emerging angle (<75), where the H+ fraction reaches similar to 100%. The unexpectedly large energy spread for the recoiled H+ spectra is attributed to the Doppler broadening caused by the zero-point energy of the vibrating H-Si system and additionally to small energy transfers among the three bodies of Ne+ and H-Si, although the assumption of binary collision between Ne+ and H is approximately valid. This H detection technique can be widely applied to analysis of chemical reactions including adsorption and desorption mediated by water and hydroxyl on various kinds of metal-oxide surfaces..
15. K. Mitsuhara, M. Tagami, T. Matsuda, A. Visikovskiy, M. Takizawa, Y. Kido, The mechanism of emerging catalytic activity of gold nano-clusters on rutile TiO2(110) in CO oxidation reaction, Journal of Chemical Physics, 10.1063/1.3697478, 136, 12, 124303, 2012.03, [URL], This paper reveals the fact that the O adatoms (O-ad) adsorbed on the 5-fold Ti rows of rutile TiO2(110) react with CO to form CO2 at room temperature and the oxidation reaction is pronouncedly enhanced by Au nano-clusters deposited on the above O-rich TiO2(110) surfaces. The optimum activity is obtained for 2D clusters with a lateral size of similar to 1.5 nm and two-atomic layer height corresponding to similar to 50 Au atoms/cluster. This strong activity emerging is attributed to an electronic charge transfer from Au clusters to O-rich TiO2(110) supports observed clearly by work function measurement, which results in an interface dipole. The interface dipoles lower the potential barrier for dissociative O-2 adsorption on the surface and also enhance the reaction of CO with the O-ad atoms to form CO2 owing to the electric field of the interface dipoles, which generate an attractive force upon polar CO molecules and thus prolong the duration time on the Au nano-clusters. This electric field is screened by the valence electrons of Au clusters except near the perimeter interfaces, thereby the activity is diminished for three-dimensional clusters with a larger size..
16. K. Mitsuhara, H. Okumura, A. Visikovskiy, M. Takizawa, Y. Kido, The source of the Ti 3d defect state in the band gap of rutile titania (110) surfaces, Journal of Chemical Physics, 10.1063/1.3697866, 136, 12, 124707, 2012.03, [URL], The origin of the Ti 3d defect state seen in the band gap for reduced rutile TiO2(110) surfaces has been excitingly debated. The probable candidates are bridging O vacancies and Ti interstitials condensed near the surfaces. The aim of this study is to give insights into the source of the gap state via photoelectron spectroscopy combined with ion scattering and elastic recoil detection analyses..
17. E. Toyoda, R. Jinnouchi, T. Hatanaka, Y. Morimoto, K. Mitsuhara, A. Visikovskiy, Y. Kido, The d-Band Structure of Pt Nanoclusters Correlated with the Catalytic Activity for an Oxygen Reduction Reaction, Journal of Physical Chemistry C, 10.1021/jp206360e, 115, 43, 21236, 2011.11, Platinum nanoclusters play an important role in catalysis. The origin of the catalytic activity is the key to improve the efficiency of the catalytic processes. One of the theory explaining catalytic properties of noble metals nanoparticles states that electronic d-band structure change with the particle size is responsible for emerging catalytic activity. To find out the actual dependence of the d-band structure of Pt nanoclusters on size we carried out the experiments using medium energy ion scattering spectroscopy and electron photoemission spectroscopy. .
18. K. Mitsuhara, H. Okumura, A. Visikovskiy, M. Takizawa, Y. Kido, Reaction of CO with O adatoms on rutile TiO2(110) surfaces, Chemical Physics Letters, 10.1016/j.cplett.2011.07.071, 513, 1-3, 84, 2011.09, [URL], The surface if rutile is known for its catalytic properties. In particular it can promote the reaction CO oxidation to CO2. The origin and mechanism of such a process are still debatable. Here we propose a model for such a process based on our study of the defects on rutile surface (oxygen vacancies and adatoms) studied quantitatively by medium energy ion scattering, elastic recoil detection and electron photoemission spectroscopy..
19. K. Mitsuhara, T. Matsuda, H. Okumura, A. Visikovskiy, Y. Kido, Oxygen deficiency and excess of rutile titania (110) surfaces analyzed by ion scattering coupled with elastic recoil detection, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS , 10.1016/j.nimb.2011.05.007, 269, 16, 1859, 2011.08, [URL], Titanium dioxide is an important material for many application. It is also a model material representing transition metal oxides (TMO). Despite of huge amount of studies include TiO2 as a substrate, there are still many controversy concerning its surface structure in terms of defects and defect electronic states. Here we used medium energy ion scattering and elastic recoil detection techniques to quantitatively characterize defects (mainly oxygen vacancy and oxiygen adatoms) depending on sample preparation conditions..
20. A. Visikovskiy, H. Matsumoto, K. Mitsuhara, T. Nakada, T. Akita, Y. Kido, Electronic d-band properties of gold nanoclusters grown on amorphous carbon, Physical Review B, 10.1103/PhysRevB.83.165428, 83, 16, 165428, 2011.04, [URL], Despite bulk gold is one of the most inert metals in periodic table, it exhibit excellent catalytic activity in the form of nano-particles and nano-clusters. There re many disputes about the origin of such catalytic properties. While many researchers claims the importance of cluster-support interaction, some stated that catalytic properties are intrinsic for gold particles and main role in this play electronic d-band structure of which changes with decreasing the size of the particle. No experimental reports on direct measurements of d-band structure depending on size of the clusters has been published so far. Here we used electron photoemission spectroscopy coupled with medium energy ion scattering technique to investigate the d-band propertied of the gold particles depending on their size. .
21. T. Yoneda, M. Shibuya, K. Mitsuhara, A. Visikovskiy, Y. Hoshino, Y. Kido, Graphene on SiC(0001) and SiC(000-1) surfaces grown via Ni-silicidation reactions, Surface Science, 10.1016/j.susc.2010.05.019, 604, 17-18, 1509, 2010.08, [URL], Conventional graphene growth on SiC surface are performed by thermal decomposition of the surface at high temperatures (>1100 degree C), this , however, not always desirable. We have shown the method of producing graphene on SiC surfaces by Ni-silicidation reaction at lower temperatures (~800 degree C). The characteristics of resulting graphene layers has been analysed by various of techniques. Interestingly graphene thickness depends on the SiC crystal orientation. While on (000-1) surface monolayer graphene can be grown by this technique, on (0001) surface double layer graphene grows..
22. K. Mitsuhara, T. Kushida, H. Okumura, H. Matsumoto, A. Visikovskiy, Y. Kido, Highly sensitive hydrogen detection by medium energy Ne(+) impact, Surface Science, 10.1016/j.susc.2010.05.018, 604, 17-18, L48, 2010.08, [URL], The quantitative analysis of hydrogen containing on the surface and near the surface is of high importance for science and application in the hydrogen related catalysis field and surface science. Being extremely light and small element hydrogen is difficult to observe by techniques conventionally used for surface composition and structure analysis. Here we have shown that it is possible to perform quantitative analysis of the H amount on the surface by high resolution elastic recoil spectroscopy using Ne ions beam. Hydrogen vibration characteristics can also be deducted from recoil energy spectrum..
23. A. Visikovskiy, M. Yoshimura, and K. Ueda, Scanning Tunneling Microscopy Study of In situ Hydrogenation of Si(110) Surface, Japanese Journal of Applied Physics, 10.1143/JJAP.49.08LB05, 49, 8, 08LB05, 2010.08, [URL], Si surface hydrogenation is an important process for application. Hydrogen can passivate the surface, play role of a surfactant in epitaxial growth of metals and so on. While hydrogenation of the Si(111) and Si(001) surfaces is well studied it is not the case for Si(110). While many researchers concentrated in developing technique of chemical hydrogenation, it is very interesting what happening when H atoms arrive at the clean surface in vacuum. Here we found a new surface structures which formed by in situ atomic hydrogen exposure on Si(110) surface. The surfaces have been analyzed by scanning tunneling microscopy (STM)..
24. H. Matsumoto, K. Mitsuhara, A. Visikovskiy, T. Akita, N. Toshima, Y. Kido, Au(core)/Pd(shell) structures analyzed by high-resolution medium energy ion scattering, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS, 10.1016/j.nimb.2010.03.032, 268, 13, 2281, 2010.07, [URL], Nanometer scale metal particles are subject of very intensive studies because of its application in catalysis. Bi-metallic core-shell structures are expected to be even more effective than mono-metallic particles. It is however extremely difficult to study the structure of such particles by usual methods, because core material is covered by the shell ind not directly accessible. Only high-resolution transmission electron microscopy can give an insight on such particle structure, which, however, lacks statistical nature. We have shown that medium energy ion scattering technique (MEIS) is capable of analyzing such core-shell structure with good precision on the example of Au/Pd core-shell particles..
25. K. Mitsuhara, Y. Kitsudo, H. Matsumoto, A. Visikovskiy, M. Takizawa, T. Nishimura, T. Akita, Y. Kido, Electronic charge transfer between Au nano-particles and TiO2-terminated SrTiO3(0 0 1) substrate, Surface Science, 10.1016/j.susc.2009.12.024, 604, 5-7, 548, 2010.03, [URL], Despite the fact that gold is the most inert metal of periodic table, it shows excellent catalytic properties in form of nanoparticles. The origin of such catalytic activity of gold is a subject of furious debates. One of the possible explanation is a charge transfer occurred on the interface between gold particles and underlying substrates. Here we studied experimentally the electronic charge transfer between gold particles and titanium dioxide and STO by medium energy ion scattering and photoemission spectroscopy. .
26. A. Visikovskiy, M. Yoshimura, and K. Ueda, Initial Stages of Platinum Silicide Formation on Si(110) Studied by Scanning Tunneling Microscopy, Japanese Journal of Applied Physics, 10.1143/JJAP.48.08Jb11, 48, 8, 08JB11, 2009.08, [URL], Si(110) surface is considered to be a candidate for future electronic devices because of its high hole mobility. It is important to study silicide formation on this surface for device application. Here we studied initial stages of Pt silicide foemation on Si(110) by scanning tunneling microscopy (STM). We found that PtSi form of the silicide is formed and determined its epitaxial relation with underlying substrate. The silicide forms in form of 3D island. However, at certain experimental conditions it is possible to produce very long (> 1 micrometer) and aligned nanowires of PtSi on Si(110)..
27. A. Visikovskiy, M. Yoshimura, K. Ueda, Pt-induced structures on Si(110) studied by STM, Applied Surface Science, 10.1016/j.apsusc.2008.01.124, 254, 23, 7626, 2008.09, [URL], Surface silicides are very important in device applications. Depending on properties of particular silicide it can form ohmic or Schottky junction with Si substrate. Platinum is an important material both for the production of semiconductor devices and in the field of catalysis. In the present work we studied different surface structures formed by Pt on the top of Si(110) surface. Si(110) surface is not so well studied especially in terms of metal adsorption comparing to (001) or (111) Si surfaces. It is, however, posses some advantageous properties such as increased hole mobility. Series of Pt surface reconstructions formed at different coverage have been observed by scanning tunneling microscopy (STM) formed on Si(110) for the first time..
28. P. Kocán, A. Visikovskiy, Y. Ohira, M. Yoshimura, K. Ueda, H. Tochihara, Magic clusters and (2×1) local structure formed in a half-unit cell of the Si(111)-(7×7) surface by Tl adsorption, Applied Surface Science, 10.1016/j.apsusc.2008.01.141, 254, 23, 7647, 2008.09, [URL], Identical clusters with enhanced stability called magic clusters. Magic clusters formed on Si(111) -(7x7) surface represent extremely dense regular array of zero-dimension structures which potentially can be utilized in different high-density memory or electronic devices. In the present work we studied formation of Tl magic clusters faulted half-unit cell of Si(111)-(7x7). Interestingly the cluster exhibit locally 2x1 structures..
29. A. Visikovskiy, H. Shibata, M.Yoshimura, K. Ueda, CAICISS and STM study of c(8×4) and (5×1) tin phases on Si(100), Surface Science, 10.1016/j.susc.2008.03.009, 602, 10, 1770, 2008.05, [URL], Several unconfirmed models of tin c(8x4) and (5x1) reconstruction on Si(100) existed so far. We applied scanning tunneling microscopy and coaxial impact collision ion scattering spectroscopy (CAICISS) to distinguish which model is correct..
30. A.A. Saranin, A.V. Zotov, M. Kishida, Y. Murata, S. Honda, M. Katayama, K. Oura, D.V. Gruznev, A. Visikovskiy, H. Tochihara, Reversible phase transitions in the pseudomorphic √7x√3-hex In layer on Si(111), Physical Review B, 10.1103/PhysRevB.74.035436, 74, 3, 035436, 2006.07, [URL], Indium produces the overlayer structure on Si(111) surface which undergoes a phase transition at low temperature. We have studied electronic and atomic structure of this phase by scanning tunnleing microscopy (STM) and low-energy electron diffraction (LEED) and proposed the mechanisms driving such reversible phase transition..
31. A. Visikovskiy, S. Mizuno and H. Tochihara, Structure of the Si(001)-(2x2)-Tl phase at 0.5 monolayer coverage, Physical Review B, 10.1103/PhysRevB.71.245407, 71, 24, 245407-245413, 2005.07, [URL], Thallium is a peculiar element. Being metal of group III of periodic table, it exhibit variable valence in chemical compounds. We have studied atomic reconstructions Tl induce on Si(001) surface by low-energy electron diffraction (LEED). It has been shown the structure formed at 0.5 monolayer coverage is very similar to the typical group III metal reconstructions on Si(001), thus at this particular conditions Tl behaves as trivalent metal. The precise coordinates of the atoms were determined. .
32. A. Visikovskiy, S. Mizuno, H. Tochihara, Reversible electromigration of Thallium adatoms on the Si(111) surface, Surface Science Letters, 10.1016/j.susc.2006.05.039, 600, 15, L189, 2006.09, [URL], In our study it has been found that Tl atoms can migrate macroscopic distances (the width of the sample) on relatively flat Si(111) surface by applying direct current to the sample. This kind of macroscopic electromigration has never been reported before. The migrating Tl produces gradient of surface coverage resulting in different surface phases along the sample..
33. V. Zavodinsky, A. Visikovskiy and I. Kuyanov, Energetics of NP and NB complexes in silicon, Computational Materials Science, 21, 4, 505-508, 2001.08, The stability of N-B and N-P atomic complexes in bulk silicon has been studied by density functional theory (DFT) calculations, as well as changes of electronic properties of active dopants by forming such complexes. This work shows that it is possible to provide nitride or oxinitride buffer layer between doped Si channel and insulating gate oxide to prevent parasitic diffusion of active dopants into the oxide layer. Dopants such as boron and phosphorous are trapped by nitrogen atoms. Formation of such complexes makes the dopants inactive..
34. V. Zavodinsky, A. Visikovskiy, I. Kuyanov, J. Dabrowski, Nitrogen trapping of boron and phosphorus in silicon, Physics of Low-Dimensional Structures, 3/4, 13-17, 2000.02, One of the problems occurred in metal-oxide field-effect transistors (MOSFET) is the diffusion of active dopants, such as boron and phosphorous from Si channel into oxide layer. This degrades the properties of insulating oxide. Introducing nitride or oxynitride buffer layer may solve the problem by trapping the diffusing dopant atoms. In the present work we have studied by density functional theory (DFT) calculations the possibility of such trapping of the boron and phosphorous by nitrogen atoms in bulk silicon..