Abstract: This paper describes our recent achievements in fabricating various kinds of nanowires of
silicon-based materials including beta iron-silicide, silicon carbide, and silicon germanium. Some of
them can be grown directly at one-step process, while the others can be fabricated using nanowire
templates. We discuss their structures, growth mechanisms, and properties based on electron
Abstract: The nano Ni-Cr thin-film samples with different composition have been fabricated by a
double-target magnetron co-sputtering equipment, through controlling the sputtering power, the
substrate rotate speed, and the substrate temperature, The results showed that the grains sizes with
polycrystalline microstructure were not greater than 10 nm. The crystal microstructure of Ni-Cr
thin-films is Face Centered Cubic (FCC). The dominant texture in the Ni-Cr film was Ni (111) under
this sputtering condition. The lattice parameters of Ni crystal and the inter-planar distances of Ni
(111) increased by Cr solid-soluble in Ni crystal. The surface morphology of the thin-film samples is
smooth and compact. The TCR (temperature coefficient of resistance) value of specimen 3 was
84~130 ppm/k, which show the specimen 3 was the most stable.
Abstract: Single-walled carbon nanotubes (SWNTs) have been synthesized on silicon nanowires
(SiNWs) by ethanol chemical vapor deposition (CVD) using Co catalysts nanoparticles. The surface
SiOx layers assist the formation of catalyst nanoparticles on SiNWs by inhibiting the diffusion of Co
to Si. Co-Si compounds have formed in SiNWs readily when the surface SiOx layers are very thin.
Therefore, the yield of SWNTs is strongly influenced by the thickness of the surface SiOx layers of
Abstract: We have studied uniform growth of crystalline Ge films on quartz plate from VHF
(60MHz)-ICP of 10% GeH4 diluted with H2 in the temperature range from 150 to 350°C. By
optimizing total gas flow rate, gas pressure, VHF power and antenna-substrate distance, the growth
rate as high as 7.4nm/s was obtained at 150°C and increased gradually up to ~7.9nm/s at 350°C. The
crystallinity, which was evaluated by Raman scattering measurements as an integrated intensity ratio
of TO phonons in crystalline phase to those in disordered phase, reached a value as high as ~93 % at
350°C, but degraded down to 64% at 150°C as a result of the formation of a 60~70nm-thick
amorphous incubation (A. I.) layer on quartz. By applying a two-step deposition method at 150°C, in
which the GeH4 concentration was selected to be 0.6% for the crystalline nucleation in the first 10s
deposition, being as thin as 10nm in thickness, and then changed to 10% GeH4 for the high rate
growth, the crystallinity was improved to 78% with keeping an effective growth rate as high as
7.5nm/s, because of a significant increase in the growth rate after the crystalline nucleation.
Abstract: We have formed high density nanodots of nickel silicide (NiSi) on ultrathin SiO2 and
characterized their electronic charged states by using an AFM/Kelvin probe technique. Si
quantum dots (Si-QDs) with an areal dot density of ~2.5x1011cm-2 were self-assembled on
~3.6nm-thick thermally-grown SiO2 by controlling the early stages of LPCVD using pure SiH4
gas. Subsequently, electron beam evaporation of Ni was carried out as thin as ~1.7nm in
equivalent thickness at room temperature and followed by 300°C anneal for 5min in vacuum.
XPS and AFM measurements confirm the formation of NiSi dots with an average dot height of
~8nm. After removal of Ni residue on SiO2 by a dilute HCl solution, bias conditions required
for electron charging to NiSi dots were compared with those to pure Si-QDs dots and Ni dots.
The surface potential changes stepwise with respect to the tip bias due to multistep electron
injection and extraction of NiSi nanodots. In addition, it is confirmed that charge retention
characteristics of NiSi dots are superior to those of Si-QDs with the almost same size.
Abstract: We investigated effect of reducing thickness of TiN buffer layers on growth of the smooth
GaN layers. The sputtered TiN layers with thicknesses in the range of 2 to 100 nm were deposited on
sapphire substrates. The sputtered TiN layers were exposed NH3 + H2 mixed gas atmosphere at about
1000°C to enrich nitrogen concentration of the layers. GaN layers were deposited on the
nitrogen-enriched TiN layer using a MOCVD method. Average grain size of the nitrogen-enriched
TiN layer was minimized at the thickness of 5 nm. In the initial stages of GaN growth, density of GaN
hexagons grown on the 5nm-thick TiN layers was the highest. The 2μm-thick GaN layers grown on
the 5nm-thick TiN layers exhibited the smoothest surface. Thus, the 5nm thickness is believed to be
the best thickness for the smooth GaN growth on the sapphire/TiN substrates.
Abstract: Aluminum nitride (AlN) thin films formed on the heat-resistant alloy substrates were
heated to 1100K. Cracking was observed in the AlN film formed on the stainless steel substrate
(SUS430), while no crack was seen in that on the nickel-base superalloy substrate (IN750X). The
electrical impedance measurements, X-ray diffraction analysis and finite element method calculation
have been conducted to discuss the relationship between the cracking and the stress introduced into
the AlN films. The AlN film cracking would be significantly affected by grain refinement of AlN.
Abstract: With the highest brilliance synchrotron radiation X-ray (SPring-8) and TEM observations,
Cu oxides ranged 2-nm to 10-nm in thickness formed on sputtered Cu has been evaluated. For the
plasma-assisted Cu oxide, weak Cu2O and/or CuO X-ray diffraction pattern is observed, while no
diffraction pattern in native and thermally (170°C) grown oxides. Those native and thermal oxides
show Cu2O coordination observed by XANES (X-ray Absorption Near Edge Structure) method. This
suggests that Cu oxide formed at low temperatures consists of stoichiometric Cu2O in an amorphous
structure. According to the Fowler-Nordheim (F-N) current emission model, the current emission
taking place at Cu2O decreases with increasing of the oxide thickness and its mean barrier height (φB)
in the MIM band structure. In case of current density at 106A/cm2 of 1V, it is estimated that the
allowable thickness of Cu oxides is approximately 1.5-nm at 1 eV of barrier height.
Abstract: Fluorocarbon polymer thin films on NiTi alloys possess extremely potential prospect. In
this paper, the preparation of thin films on NiTi alloys by radio-frequency (RF) magnetron sputtering
from polytetrafluoroethylene (PTFE) targets under argon is introduced. Sputtered fluorocarbon thin
films on NiTi alloys are characterized by means of atomic force microscopy (AFM), X-ray
photoelectron spectroscopy (XPS) and attenuated total reflection Fourier transform infrared
spectroscopy (ATR-FTIR) and their basic properties, especially structure and morphology, are
Abstract: The electrical and optical properties, and microstructures of 100 nm-thick Ga2O3 films
fabricated on Al2O3(0001) substrates by a sputtering deposition were investigated. The partial
pressure of oxygen was controlled and the substrate temperature was kept to be 500 °C during
deposition. With increasing the oxygen partial pressure, the structures of the Ga2O3 films deposited
on the substrates were observed to change from amorphous to crystalline (monoclinic β-type Ga2O3).
The transmittance of the Ga2O3 films was measured to be more than 80 % at the visible and ultraviolet
regions although the electrical resistivity was high. In order to obtain both low electrical resistivity
and high transmittance at the ultraviolet regions, the addition of active dopant elements such as Sn
into the Ga2O3 films would be required.