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Since the pioneering work by Novoselov and Geim in 2004 [1], graphene has attracted skyrocketing attention as a new electronic material. Behind this enthusiasm are the fundamental limitations that silicon is facing, which impede further scaling of Si devices down into sub-10 nm regions. In this respect, the expectation for graphene is two-fold: medium term and long term. As for the former, the expectation as a new channel material in field-effect transistors (FET) is at its center (More Moore strategy). As for the latter, graphene’s novel quantum properties are expected to bring about new paradigm of information processing (Beyond CMOS strategy). The fact that many quantum phenomena, such as quantized Hall effect [2] and spin-polization of the current [3], can be observed at room temperatures in graphene, which is not usual in other materials, fuels the trend.

By employing a pulsed-discharge, near-atmospheric-pressure plasma-enhanced chemical vapor deposition, equally qualified pair of poly-Si films are grown on polyethylene terephthalate (PET) substrates placed at both the grounded and the powered electrodes. This finding leads to a roll-to-roll-type deposition system of cleaning-free operation for film growth.

Kinetics of initial oxidation of Si(110)-16x2 surface has been investigated by using real-time photoemission spectroscopy. One of the most striking features of Si(110) oxidation, in comparison with that of Si(001) surface, is the occurence of an extremely rapid oxidation in its early stage. Only 15 s after introduction of ~10^-5-Pa oxygen molecules, the Si(110) surface at 540 deg-C is already covered with 0.3-monolayer oxide. This rapid initial oxidation can be related to oxidation at or around the adatom clusters which are reportedly the major constituent of the 16x2 reconstruction on this Si(110) surface.

Growth of highly crystalline poly-Si films on polyethylene terephthalate (PET) substrates at 150 {degree sign}C has been achieved with practical growth rates by using pulsed-plasma CVD under near-atmospheric pressure. The precursor is SiH4 diluted in H2, and no inert gases such as He were used. A short-pulse based power system has been employed to maintain a stable discharge in the near-atmospheric pressures. By using this technique we have succeeded in growth of poly-Si thin film on the glass substrate at 180 {degree sign}C with virtually no incubation layers. Good crystallinity of the poly-Si thin films were observed by Raman scattering spectroscopy and cross-sectional transmission electron microscopy.

Heteroepitaxial growth of 3C-SiC on Si(110) substrate has been successfully conducted at T=1000{degree sign}C by using monomethylsilane as a single source gas. X-ray diffraction (XRD) reveals that the growth orientation of the film is rotated and a 3C-SiC (111) film is formed on this Si(110) substrate. The film quality, as evaluated with the half width of the XRD rocking curve, shows betterment from that of 3C-SiC(111)/Si(111) film. The lattice constant anisotropy (a//-a⊥)/a// between the lateral and the growth directions also decreased by a factor of four from that of 3C-SiC(111)/Si(111), and the two lattice constants approach to that of bulk 3C-SiC. These results indicate significant reduction in the strain of the 3C-SiC film in this 3C-SiC(111)/Si(110) system. XRD-scan indicates presence of double domains with almost equal areas.

Ge nanodots were formed on Si(001) 2˚-off substrates after formation of a Si-c(4×4) structure by gas-source molecular beam epitaxy using monomethylgermane as a source gas. Surface structures of the Ge nanodots were measured using reflection high-energy electron diffraction and scanning tunneling microscopy. Photoluminescence spectra of the Ge nanodots capped with SiC layers measured at low temperature exhibited intense peaks around 1.07 and 1.01 eV, which are considered to be originated from the Ge(GeCx) nanodots.

Graphene-on-silicon field-effect transistors (GOSFETs) are studied as a candidate of next generation transistors. Graphene is formed on SiC layers grown on Si substrates. As well as the channel material, the gate stack is also a key component of FETs. In this study, SiCN deposited by plasma-enhanced chemical vapor deposition (PECVD) using hexamethyldisilazane (HMDS) vapor is studied. During PECVD, hydrogen is used as a carrier gas in addition to HMDS vapor. This becomes an advantage in the graphene process because hydrogen has cleaning effect on graphene surface. To verify this effect, SiCN gate stack is applied to the graphene on SiC substrates. FETs with SiCN gate stack exhibit clearer ambipolar characteristics and larger drain current density than FETs with conventional SiN gate stack. The SiCN gate stack is also applied to GOSFETs. Resulting devices also exhibit ambipolar characteristics and larger current density than previously reported GOSFETs with SiN gate stack.

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