Tomonori Ikari

AN STM OBSERVATION OF ADSORPTION OF CuPc ON THE Si(100) SURFACE WITH Bi-LINE STRUCTURES

We report the reaction dynamics of the Bi-line structure (BLS) with copper-phthalocyanine (CuPc)molecules as well as hydrogen and Ag atoms on Si(100) surfaces observed by scanning tunneling microscopy. Co-adsorption of hydrogen and Ag on the Si(100) surface with BLSs brought about agglomeration of Ag atoms on the Si terrace. When CuPc molecules were deposited on the Si(100) surface with BLSs at room temperature, domains with c(4 × 4) periodicity appeared in the terraces near the BLS. When the surface was annealed at 200°C–400°C, the area of the c(4 × 4) domain was increased. The CuPc molecules, adsorbed on BLS, were possibly dissociated by catalytic reaction of Bi atoms.

Ion-Beam Irradiation Effect in the Growth Process of Graphene on Silicon Carbide-on-Insulator Substrates

We investigated the effect of ion-beam irradiation of the 3C-SiC(111) surface on the growth of graphene by the SiC surface-decomposition method. When a 3C-SiC(111) surface was irradiated by 1 keV Ar+ ions at a dose of 4.5 × 1015 cm2 in an ultra-high-vacuum chamber and then annealed at 1200 °C for 1 min, the formation of graphene layers was promoted in comparison with that in the absence of ion-beam irradiation. X-ray photoelectron spectroscopy studies showed that Ar ion bombardment of the 3C-SiC(111) caused breakage of surface bonds and helped Si atoms to desorb from the surface.

STM OBSERVATION OF GRAPHENE FORMATION USING SiC-ON-INSULATOR SUBSTRATES

We used scanning tunneling microscopy to investigate graphene formation on an SiC-on-insulator (SiC-OI) substrate. Annealing of an SiC-OI substrate with an SiC thickness of 1500 nm produced a graphene layer on the SiC surface. When the thickness of the SiC film was 5 nm, a graphene layer was not formed on the SiC surface. However, after annealing a C-covered SiC-OI substrate with an SiC thickness of 5 nm, a graphene layer formed on the SiO2 surface.

Effect of ion-beam irradiation on the epitaxial growth of graphene via the SiC surface decomposition method

We used scanning tunneling microscopy, low-energy electron diffraction, and Raman spectroscopy to investigate the growth of graphene on 3C-SiC(111)/SiO2/Si(111) surfaces with ion-beam irradiation via the SiC surface decomposition method. We were unable to obtain graphene after annealing the 3C-SiC(111) surface at 1100 °C for 3 min without Ar+ ion-beam irradiation. When a 3C-SiC(111) surface was irradiated with an Ar+ ion beam at an acceleration voltage of 1 keV and an incident angle of 80° and subsequently annealed at 1100 °C for 3 min, graphene formed on the SiC surface. However, when an Ar+ ion beam was used at an incident angle of 70 or 60°, graphene layers were not formed. These results indicate that the breakage of bonds in the surface region of the SiC(111) substrate by ion-beam irradiation promotes the formation of graphene.

Ion-Beam Irradiation Effect on the Growth of Carbon Nanotubes in the SiC Surface Decomposition Method

We investigated the influence of ion-beam irradiation of the SiC(000) surface on the growth of carbon nanotubes (CNTs) by the SiC surface decomposition method. After an SiC(000) surface was irradiated by Ar+ ions at 1 keV with a dose of 4.5×1015 cm-2 in an ultrahigh vacuum chamber, and then annealed at 1700 °C for 2 h at a pressure of 2×10-2 Pa, CNTs formed on the surface that were longer than CNTs grown without ion-beam irradiation. When 5 keV Ar+ ions were used, no CNTs formed, but instead an amorphous carbon layer formed on the surface.

INFLUENCE OF A Cr LAYER ON THE GLASS SUBSTRATE ON THE GROWTH OF CARBON NANOTUBES BY CHEMICAL VAPOR DEPOSITION

We report the effect of a Cr layer on the glass substrate during the growth of carbon nanotubes (CNTs) by chemical vapor deposition. When Fe was used as a catalyst in the CNT growth, longer CNTs were obtained by increasing the thickness of the Cr layer. However, CNTs were not grown on the surface with a thick Cr film and Co or Ni catalyst. These results arise from a difference in the mechanism of CNT formation when using different catalyst metals.