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Journal Articles

In situ SR-XPS observation of Ni-assisted low-temperature formation of epitaxial graphene on 3C-SiC/Si

Hasegawa, Mika*; Sugawara, Kenta*; Suto, Ryota*; Sambonsuge, Shota*; Teraoka, Yuden; Yoshigoe, Akitaka; Filimonov, S.*; Fukidome, Hirokazu*; Suemitsu, Maki*

Nanoscale Research Letters, 10, p.421_1 - 421_6, 2015/10

 Times Cited Count:11 Percentile:48.8(Nanoscience & Nanotechnology)

Graphene has attracted much attention as a promising material in electronics and photonics. The graphitization temperature of 1473 K or higher of graphene-on-silicon(GOS), however, is still too high to be fully compatible with the Si technology. Here, the first application of Ni-assisted formation of graphene to the GOS method was reported. We demonstrate that the graphene formation temperature can be reduced by more than 200 K by this method. Moreover, solid-phase reactions during heating/annealing/cooling procedures have been investigated in detail by using ${{it in-situ}}$ synchrotron-radiation X-ray photoelectron spectroscopy. As a result, we clarify the role of Ni/SiC reactions, in which not only Ni silicidation and but also Ni carbonization is suggested as a key process in the formation of graphene.

Journal Articles

Formation of epitaxial graphene on Si substrates and its evaluation by high resolution synchrotron radiation photoemission spectroscopy

Suemitsu, Maki*; Fukidome, Hirokazu*; Teraoka, Yuden

NanotechJapan Bulletin (Internet), 7(2), 5 Pages, 2014/04

no abstracts in English

Journal Articles

Direct measurement of surface stress during Bi-mediated Ge growth on Si

Asaoka, Hidehito; Yamazaki, Tatsuya*; Yamaguchi, Kenji; Shamoto, Shinichi; Filimonov, S.*; Suemitsu, Maki*

Surface Science, 609, p.157 - 160, 2013/03

 Times Cited Count:1 Percentile:5.74(Chemistry, Physical)

We have focused on stress measurements during Bi termination of Si(111) and Ge growth on this Bi-mediated Si(111). In order to obtain information on both the surface stress and the surface structure simultaneously, we have combined the surface-curvature and the reflection-high-electron-energy-diffraction instrumentations in an identical ultrahigh vacuum system. We find the Bi-terminated Si(111) $$sqrt{3}$$$$times$$$$sqrt{3}$$-$$beta$$ surface releases 1.8 N/m (=J/m$$^{2}$$), or (1.4 eV/(1$$times$$1 unit cell)), of the surface energy from the strong tensile Si(111) 7$$times$$7 reconstruction. Subsequent Ge deposition on the Bi-terminated Si surface develops a compressive stress, which oscillates with a period corresponding to the growth of a single bilayer. The real-time stress measurement provides a direct evidence for this oscillatory stress relaxation in the layer-by-layer growth.

Journal Articles

Epitaxy of graphene on 3C-SiC(111) thin films on microfabricated Si(111) substrates

Ide, Takayuki*; Kawai, Yusuke*; Handa, Hiroyuki*; Fukidome, Hirokazu*; Kotsugi, Masato*; Okochi, Takuo*; Enta, Yoshiharu*; Kinoshita, Toyohiko*; Yoshigoe, Akitaka; Teraoka, Yuden; et al.

Japanese Journal of Applied Physics, 51(6), p.06FD02_1 - 06FD02_4, 2012/06

 Times Cited Count:7 Percentile:33.93(Physics, Applied)

Journal Articles

Controls over structural and electronic properties of epitaxial graphene on silicon using surface termination of 3C-SiC(111)/Si

Fukidome, Hirokazu*; Abe, Shunsuke*; Takahashi, Ryota*; Imaizumi, Kei*; Inomata, Shuya*; Handa, Hiroyuki*; Saito, Eiji*; Enta, Yoshiharu*; Yoshigoe, Akitaka; Teraoka, Yuden; et al.

Applied Physics Express, 4(11), p.115104_1 - 115104_3, 2011/11

 Times Cited Count:34 Percentile:80.78(Physics, Applied)

Journal Articles

Control of epitaxy of graphene by crystallographic orientation of a Si substrate toward device applications

Fukidome, Hirokazu*; Takahashi, Ryota*; Abe, Shunsuke*; Imaizumi, Kei*; Handa, Hiroyuki*; Kang, H. C.*; Karasawa, Hiromi*; Suemitsu, Tetsuya*; Otsuji, Taiichi*; Enta, Yoshiharu*; et al.

Journal of Materials Chemistry, 21(43), p.17242 - 17248, 2011/11

 Times Cited Count:28 Percentile:67.71(Chemistry, Physical)

Journal Articles

Low-energy-electron-diffraction and X-ray-phototelectron-spectroscopy studies of graphitization of 3C-SiC(111) thin film on Si(111) substrate

Takahashi, Ryota*; Handa, Hiroyuki*; Abe, Shunsuke*; Imaizumi, Kei*; Fukidome, Hirokazu*; Yoshigoe, Akitaka; Teraoka, Yuden; Suemitsu, Maki*

Japanese Journal of Applied Physics, 50(7), p.070103_1 - 070103_6, 2011/07

 Times Cited Count:31 Percentile:78.66(Physics, Applied)

Journal Articles

Oxygen-induced reduction of the graphitization temperature of SiC surface

Imaizumi, Kei*; Handa, Hiroyuki*; Takahashi, Ryota*; Saito, Eiji*; Fukidome, Hirokazu*; Enta, Yoshiharu*; Teraoka, Yuden; Yoshigoe, Akitaka; Suemitsu, Maki*

Japanese Journal of Applied Physics, 50(7), p.070105_1 - 070105_6, 2011/07

 Times Cited Count:4 Percentile:20.9(Physics, Applied)

Journal Articles

Initial oxidation of Si(110) as studied by real-time synchrotron-radiation X-ray photomission spectroscopy

Suemitsu, Maki*; Yamamoto, Yoshihisa*; Togashi, Hideaki*; Enta, Yoshiharu*; Yoshigoe, Akitaka; Teraoka, Yuden

Journal of Vacuum Science and Technology B, 27(1), p.547 - 550, 2009/02

 Times Cited Count:4 Percentile:31.09(Engineering, Electrical & Electronic)

Initial oxidation processes of the Si(110) surface and the chemical bonding states of silicon atoms in the initial oxides have been investigated by using real-time synchrotron-radiation photoemission spectroscopy. Time evolutions of the Si$$^{n+}$$ ($$n$$=1-4) components in the Si 2$$p$$ spectrum indicates that the Si$$^{3+}$$ component always overwhelms the Si$$^{4+}$$ component during the oxidation up to one monolayer. This is in sharp contrast to the Si(001) surface where Si$$^{4+}$$ is always larger than Si$$^{3+}$$. The dominance of the Si$$^{3+}$$ component is related to presence of two types of bonds on the Si(110) surface and to their possible different reactivity against insertion of oxygen atoms.

Journal Articles

Initial oxidation of Si(110) surface evaluated by photoemission spectroscopy and substrate-curvature measurements

Yamamoto, Yoshihisa*; Suzuki, Yasushi*; Miyamoto, Yu*; Bantaculo, R.*; Suemitsu, Maki*; Enta, Yoshiharu*; Teraoka, Yuden; Yoshigoe, Akitaka; Asaoka, Hidehito; Yamazaki, Tatsuya

Hakumaku, Hyomen Butsuri Bunkakai, Shirikon Tekunoroji Bunkakai Kyosai Tokubetsu Kenkyukai Kenkyu Hokoku, p.207 - 210, 2009/01

The bending of Si substrate has been measured optically in the oxidation of Si(110) surface and variation of curvature for (001) and (-110) directions have been evaluated. Furthermore, time evolutions of oxygen adsorption content and its chemical bonding states have been measured by photoemission spectroscopy to discuss inisotropy of the Si(110) oxidation in comjunction with substrate curvature measurements. Oxygen adsorption content was evaluated from O1s photoemission and chemical bonding states were evaluated from Si2p photoemission. O$$_{2}$$ gas pressure was ranging from 5.0$$times$$10$$^{-6}$$ Pa to 6.7$$times$$10$$^{-6}$$ and substrate temperature was 873 K. Compressive stress was detected in the (-110) direction. In turn, stretching stress was detected. The photoemission spectroscopy indicated that a layer-by-layer oxidation was not took place. The stretching stress in the (001) direction implies that oxidation of B-bonds which have components along the (001) direction takes place.

Journal Articles

SR-PES and STM observation of metastable chemisorption state of oxygen on Si(110)-16$$times$$2 surface

Yamamoto, Yoshihisa*; Togashi, Hideaki*; Kato, Atsushi*; Takahashi, Yuya*; Konno, Atsushi*; Teraoka, Yuden; Yoshigoe, Akitaka; Asaoka, Hidehito; Suemitsu, Maki*

Applied Surface Science, 254(19), p.6232 - 6234, 2008/07

 Times Cited Count:4 Percentile:23.21(Chemistry, Physical)

The room temperature adsorbed state of oxygen molecules on Si(110)-16$$times$$2 surface and the structural change after a mild annealing has been investigated by synchrotron radiation photoemission spectroscopy. As a result, despite the very small dosage of oxygen, Si$$^{2+}$$ and Si$$^{3+}$$ components already appear in addition to Si$$^{1+}$$. This is likely to be caused by a selective adsorption of O$$_{2}$$ molecules into the vicinity of already oxidized sites. After annealing, we found that binding energy of Si$$^{2+}$$ and Si$$^{3+}$$ increase and approach to their corresponding peak positions of a thermally-grown oxide, and this increase indicates relaxation of the Si-O bond length and Si-O-Si bond angle of metastable oxygen atoms.

Journal Articles

XPS real-time monitoring on the development of Si suboxides during formation of thermal oxides on Si(110) surface

Yamamoto, Yoshihisa*; Togashi, Hideaki*; Konno, Atsushi*; Matsumoto, Mitsutaka*; Kato, Atsushi*; Saito, Eiji*; Suemitsu, Maki*; Teraoka, Yuden; Yoshigoe, Akitaka

Shingaku Giho, 108(80), p.65 - 70, 2008/06

The growth process of thermal oxides on Si(110) surface and the development of their interfacial bonding structures have been investigated by using real-time synchrotron radiation photoemission spectroscopy. As a result, it was clarified that the Si$$^{3+}$$ component in the Si 2p core-level spectra is always much higher than that of Si$$^{4+}$$ for 0-1 mono-layer (ML) oxides on Si(110) surface. Observations on the time-evolution of the O 1s core-level spectrum indicates that the autocatalytic-reaction model proposed for the Si(001) oxidation can be also applicable to the Si(110) oxidation.

Journal Articles

Bonding structure of ultrathin oxides on Si(110) surface

Yamamoto, Yoshihisa*; Togashi, Hideaki*; Kato, Atsushi*; Suemitsu, Maki*; Narita, Yuzuru*; Teraoka, Yuden; Yoshigoe, Akitaka

Materials Research Society Symposium Proceedings, Vol.1074, p.36 - 40, 2008/00

In this study, we have investigated the bonding structure of ultrathin oxide films on Si(110) surface by real-time SR-PES experiments. Experiments were conducted at surface chemistry end-station settled at BL23SU in SPring-8. The oxidation temperature was 813 K and the O$$_{2}$$ pressure was 1.1$$times$$10$$^{-5}$$ Pa. As a result, we found that one of the surface core-level shifts in Si 2p spectrum, related to the 1st and the 2nd layer Si atoms, decreases rapidly, coincident with the rapid initial development of the O1s spectrum. This indicates high reactivity of the Si(110)-16$$times$$2 reconstructed surface with oxygen molecules.

Journal Articles

Real-time stress measurement in Ge/Si(111)-7$$times$$7 heteroepitaxial growth

Asaoka, Hidehito; Yamazaki, Tatsuya; Shamoto, Shinichi; Arnoldo, A.*; Goto, Seiichi*; Suemitsu, Maki*

Hyomen Kagaku, 28(9), p.500 - 503, 2007/09

Stress evolution during initial stage of Ge nanodot formation on Si(111)-7$$times$$7 has been investigated by using simultaneous measurements of the substrate curvature and the surface morphology. In the beginning of the first bilayer growth of Ge on Si(111)-7$$times$$7, a strong compressive film stress is observed, indicating a formation of a two-dimensional wetting layer. When the layer thickness approaches the critical one for three-dimensional nanodot nucleation, a clear bend in the stress curve is observed, corresponding to a partial relaxation of the lattice planes on the surface of the nanodots. Moreover, a stress transition has been also found to exist in the very early stage of the nanodot formation, which is concurrent with the trench formation around the three-dimensional nanodots.

Journal Articles

Observation of initial oxidation on Si(110)-16$$times$$2 surface by scanning tunneling microscopy

Togashi, Hideaki*; Takahashi, Yuya*; Kato, Atsushi*; Konno, Atsushi*; Asaoka, Hidehito; Suemitsu, Maki*

Japanese Journal of Applied Physics, Part 1, 46(5B), p.3239 - 3243, 2007/05

 Times Cited Count:13 Percentile:48.98(Physics, Applied)

On Si(110) surface, the hole mobility is enhanced as compared with that on Si(001) surface. This surface is also to be used in the next-generation three-dimensional devices. We conducted scanning-tunneling-microscopy (STM) observation on the initial oxidation of Si(110)-16$$times$$2 surface. The present result suggests less occurrence of etching under the oxidation condition. There is a possibility to form an abrupt oxide/Si interface on the Si(110) surface.

Journal Articles

Real-time observation of initial thermal oxidation on Si(110)-16$$times$$2 surfaces by O 1s photoemission spectroscopy using synchrotron radiation

Suemitsu, Maki*; Kato, Atsushi*; Togashi, Hideaki*; Konno, Atsushi*; Yamamoto, Yoshihisa*; Teraoka, Yuden; Yoshigoe, Akitaka; Narita, Yuzuru*; Enta, Yoshiharu*

Japanese Journal of Applied Physics, Part 1, 46(4B), p.1888 - 1890, 2007/04

 Times Cited Count:12 Percentile:46.58(Physics, Applied)

Initial oxidation of Si(110) surface has been investigated by using real-time X-ray photoemission spectroscopy. The time evolution of the O 1s spectrum shows occurrence of rapid oxidation just after the introduction of the oxygen molecules, which is evidenced by the considerable peak intensity corresponding to oxygen exposure of as low as 1.5L (1L=1.33$$times$$10$$^{-4}$$ Pa s). This initial oxide is dominated by a state with a relatively low binding energy, which is gradually replaced by a state with a relatively high binding energy with the increase of the oxygen exposure, resulting in the low-KE shift of the O 1s peak. Comparison with previously reported O 1s spectra from dry-oxidized Si(111) surface suggests oxidation at or around the adatoms of Si(110)-16$$times$$2 clean surface as a likely oxidation state for this low-binding-energy peak.

Journal Articles

XPS and STM studies on initial oxidation of Si(110)-16$$times$$2

Suemitsu, Maki*; Togashi, Hideaki*; Kato, Atsushi*; Takahashi, Yuya*; Konno, Atsushi*; Yamamoto, Yoshihisa*; Teraoka, Yuden; Yoshigoe, Akitaka; Asaoka, Hidehito

Materials Research Society Symposium Proceedings, Vol.996, p.19 - 25, 2007/00

From its high hole mobility, as well as its inevitable usage as an active layer in multi-gated FETs, Si(110) surface is expected to play a crucial role in the next generation CMOS devices. We have investigated the initial oxidation of Si(110) surface by using SR-XPS and STM. Reflecting its atomistic structure of the 16$$times$$2 reconstruction, initial oxidation of Si(110) surface shows a unique behavior which is not observed on other surfaces like (111) and (001).

Journal Articles

Comparison of initial oxidation between Si(110) and Si(100) surfaces; From real-time photoemission spectroscopy

Suemitsu, Maki*; Kato, Atsushi*; Togashi, Hideaki*; Konno, Atsushi*; Yamamoto, Yoshihisa*; Teraoka, Yuden; Yoshigoe, Akitaka; Narita, Yuzuru*

Shingaku Giho, 106(108), p.61 - 63, 2006/06

no abstracts in English

Journal Articles

Real-time observation of initial thermal oxidation on Si(110)-16$$times$$2 surface by photoemission spectroscopy

Suemitsu, Maki*; Kato, Atsushi*; Togashi, Hideaki*; Konno, Atsushi*; Yamamoto, Yoshihisa*; Teraoka, Yuden; Yoshigoe, Akitaka; Enta, Yoshiharu*; Narita, Yuzuru*

ECS Transactions, 3(2), p.311 - 316, 2006/00

Initial thermal oxidation of Si(110) surface has been investigated by using real-time X-ray photoemission spectroscopy with synchrotron radiation. The Si(110) initial oxidation is characterized by presence of a rapid oxidation just after the introduction of gaseous oxygen molecules. Peak separation of the O1s photoemission spectra suggests the presence of at least two distinct oxidation sites on the surface, which may reflect the complicated surface structure of the Si(110)-16$$times$$2 reconstruction.

Journal Articles

Nucleation of oxides during dry oxidation of Si(001)-2$$times$$1 studied by scanning tunneling microscopy

Togashi, Hideaki*; Asaoka, Hidehito; Yamazaki, Tatsuya; Suemitsu, Maki*

Japanese Journal of Applied Physics, Part 2, 44(45), p.L1377 - L1380, 2005/10

 Times Cited Count:3 Percentile:14.36(Physics, Applied)

no abstracts in English

86 (Records 1-20 displayed on this page)