We have created what we term an “MTP-micelle”; that consists of self-assembled alkanethiols adsorbed on the surface of a Au multiply-twinned particle (MTP). Some potential applications of these MTP-micelles include preparation of novel metal thin film structures.
Electrolyte/metal interface is interesting as the place of producing material because we can control the process dynamics by means of applied potential to metal. In this paper, we electrodeposited CdTe thin films on Au(111)/polyethylene in 50mM H2SO4+1mM CdSO4+0.1mM TeO2 aqueous solution. The electrodeposited thin films were investigated by X-ray Photoelectron Spectroscopy (XPS), Electro-Chemical Atomic Force Microscopy (EC-AFM) and electrochemical measurement. The film electrodeposited at-1000mV (vs. Hg/Hg2SO4) consisted mainly of CdTe compound and was much less oxidizable than Cd film and Te film. Based on the result of in-situ EC-AFM measurement, we ascertained the CdTe deposition mechanism under this condition.
Rusts of iron and steels have been so familiar to us since the ancient Iron Age. Over the last decades, substantial progress has been made in understanding the formation of rust and its structure. Techniques for controlling the structures and properties of rust layers have also been developed that are capable of protecting steel surfaces from atmospheric corrosion. In this article, we mention first what rusting is, and then the structures including [rust/steel] interfacial structure and protective ability of rust layers. Latest rust controlling technologies are also shown.
Surface modification by low-temperature plasma was reviewed. Plasma treatments of powders and fibers (fabrics) were focused, and the literatures published last five years concerning the treatments were introduced and discussed. In the plasma treatment of powders, some good devices for the reactor systems are required for uniform and efficient treatments. Recently, plasma-induced graft polymerization has been applied to powdery materials, which are expected to be used as new dispersing particles in hybrid systems. In the plasma treatment of fibers, many kinds of fibers have been proceeded for different purposes. Recently, high-strength fibers, such as aramid and carbon fibers, are often treated by plasma for the use of fiber-reinforced plastic (FRP). The strength of the FRPs with those plasma-treated fibers has been improved.
Layer-by-layer oxidation of Si surfaces has been studied by scanning reflection electron microscopy, which allowed us to obtain plan-view images of buried SiO2/Si interfaces. We observed atomic steps at the SiO2/Si(111) interfaces and the periodic reversal of terrace contrast during oxidation of Si(001) surfaces. We found that the initial surface structure was preserved at the interface and that the interfacial steps did not move laterally during oxidation. These results mean that layer-by-layer oxidation is governed by random nucleation of nanometer-scale oxide islands and lateral island growth. We also studied the kinetics of initial layer-by-layer oxidation of Si(001) surfaces. Our results showed that barrier-less oxidation of the first sub-surface layer, as well as oxygen chemisorption onto the top-layer, occurred at room temperature. The energy barrier of the second-layer oxidation was found to be 0.3eV. The initial oxidation kinetics is discussed based on first-principles calculations.
A delta-function-shaped Sb doping spike in Si is prepared by deposition of Sb on a Si(001) surface followed by lowtemperature molecular beam epitaxy of Si. The depth profile of the Sb atoms is measured using high-resolution Rutherford backscattering spectroscopy, yielding a depth resolution of 0.3nm. The observed profile shows two peaks conesponding to the delta-doped layer (of width 0.5nm) and Sb atoms on the surface. The latter are due to surface segregation of Sb atoms during the growth of the Si cap layer. The surface segregation rate is derived from the observed results at temperatures 70-280°C. It is larger than the value extrapolated from high- temperature (>400°C) data by several orders of magnitude and shows a very weak temperature dependence as compared to the high-temperature data. These features indicate a new surface segregation mechanism at low temperature. A mechanism for this anomalous segregation is discussed.
GaAs(001) is one the most commonly used substrates in fabrication of wireless and opto-electronic devices based on III-V compound semiconductors by using molecular beam epitaxy (MBE), metallorganic chemical vapor deposition (MOCVD) and related techniques. The surface structure of GaAs(001) has been disputed since the beginning of the development of the techniques as to which of these materials are artificially prepared. The invention of scanning tunneling microscopy (STM) has revolutionized the situation. This paper reviews the STM studies of principal reconstructions, from As-rich c(4×4), 2×4, 2×6 to Ga-rich 4×2 and 4×6, found on the GaAs(001) surface. These studies, together with advanced theoretical efforts, have eventually resulted in establishment of a unified model for various reconstructions, with which we could explain most of the observation and long-standing controversies in atomic structures and surface stoichiometries.
We discuss the interaction of bulk phonons with surface vibrational modes in a finite-size superlattice. The incident phonons injected normally on the superlattice from a substrate are perfectly reflected, i.e., the reflection ratee is unity irrespective of frequency. However, these phonons come back to the substrate with a large time delay when the frequency coincides with an eigenfrequency of the surface mode. This is due to the resonant interaction of the incident phonons with a surface vibrational mode. The results suggest that the surface vibrational modes are detectable from the other side of the surface by a time-resolved phonon reflection experiment.
The energy distribution of interface states in the Si band-gap present at ultra-thin silicon oxide/Si interfaces is obtained from XPS measurements under bias. The substrate Si 2p peak for the <Pt/silicon oxide/Si> MOS structure is shifted by the application of a bias voltage to the Si with respect to the Pt, due to the accumulation of charges in the interface states in the Si band-gap. The energy distribution of interface states can be obtained from measurements of the bias-induced shift of the Si 2p peak as a function of the bias voltage. All the observed interface state spectra have peaked-structure, and the number of' the peaks and their energies depend on the oxide formation method. From comparison with theoretical calculations, the observed interface state peaks are attributed to Si dangling bonds in various environments. The variation in the interface state spectra is attributed to different atomic densities of the oxide layers. The formation of Si-CN bonds at the interface using cyanide treatment is found to decrease the interface state density markedly. The cyanide treatment improves the electrical characteristics of the MOS tunneling diodes.
Theoretical studies on the metal-aqueous electrolyte solution interface are critically reviewed with emphasis on the studies using quantum treatments for the metal side and classical approaches, above all, integral equation theories, for the solution side. With the integral equation theories an infinitely large system can be mimicked, and ions can readily be incorporated in the solvent at a finite concentration. The density structure of water molecules and ions, water and ion configurations near the metal surface, and the potential drop across the interface are discussed and some of them are compared with experimental observations. Future subjects to be considered such as how to connect the quantum system with the classical system in a more realistic manner, are also discussed.