According to the recently fabricated silicon device technology, the thickness of gate oxide has become only a few nanometers. So the effect of device characteristics resulted from the flatness of SiO2/Si interface and the bonding state of the transition region can not be neglected. Recently total low-temperature process is taken into account in order to avoid the mechanical stress caused by thermal-expansion-coefficient difference of Si, SiO2 and interconnected metals. Plasma oxidation is a technique being used for growing insulator films on semiconductor surfaces at lower temperatures than those used for thermal oxidation. On the other hand, computational chemistry has become a powerful tool to obtain useful information that can not be provided by the experiments. In this study, we performed plasma oxidation simulation using tight-binding molecular dynamics, the oxygen species are emitted over the substrate and the structure of constructed SiO2 film was discussed.
A procedure for the identification of organic compounds by inference and re-classification of Ga primary ion TOF-SIMS fragments is proposed. The procedure is capable of rapid identification of newly appeared organic compounds or/and of them during the synthetic process. In this experiment, considering that this method might be applied to the polymer surface analysis we employed polymer additives: 4-hydroxy-3,5-di-t-butyl phenyl propionate group and related ones, as examples. Fragments appeared in the mass spectra could be inferred considering raw materials for synthesis, functional radicals that may consist of fragments from organic compounds, and the synthesis process of the sample compounds. Further, employing ca. 70 polymer additives, an identification procedure of some organic compounds was proposed, in which the identification could be performed through several stages of classification programs of fragment structures (formulas) inferred from the mass spectra of measured organic compounds.
Impurity inclusions in electrodeposited films can be imaged using a transmission electron microscope. Phase contrast by defocusing is used to detect small impurity molecules directly, whereas amplitude (diffraction) contrast is applied to image small strain fields associated with impurity inclusions. Principles of the phase/diffraction contrast for this application are described together with applications to several experimental results from microstructural studies on electrodeposited films.
For the purpose of developing high performance hydrodesulfurization catalyst, increased numbers of work, based on precise analysis of catalyst active site structure using model support technique, have been carried out. Among those, we introduce following very attractive works. i.e. structural analysis of MoS2 clusters in atomic level by SPM, precise analysis of sulfidation mechanism by XPS, and study of the effect of support on the orientation of MoS2 clusters by HRTEM. New high performance catalysts are expected to be developed thorough these approach of surface science.
Effect of interfacial tension on the structure and mechanical properties of molten immiscible polymer blends has been studied. Following a rheological constitutive equation proposed by Palierne, the interfacial tension is estimated from the viscoelastic properties. In this paper, the values of interfacial tension for various kinds of polyolefin pairs are summarized. The interfacial tension is responsible for the phase separated structure of immiscible polymer blends. The size of the dispersed phase decreases with decreasing the interfacial tension. Moreover, adding a compatibilizer that is a block or graft copolymer of an immiscible polymer pair exerts a significant influence on the structure of the blend. Locating between the different phases, the compatibilizer prevents disperse particles from coalescing together during the mixing process and, as a result, the size of particles decreases.
Atomic-layer etching and electron-stimulated desorption of Br-chemisorbed Si(111)-7×7 surfaces were investigated by scanning tunneling microscope. In a Br2 dose of 100 L, most of the Si adatoms are saturated with Br atoms, while the 7×7 structure is completely retained. In further Br2 doses up to 400 L, most of the Si adatoms are etched, and the underlying rest-atom layer is imaged during the tip scanning at a sample bias of +3 V. Irradiating Br-chemisorbed surfaces with the field-emitted electrons from an STM tip, which was farther away from the sample than at usual observation, induced various desorption behavior depending on the initial Br coverage and electron energy. At low Br coverage, Br atoms desorb but no atomical changes on the Si surface occur. At saturation coverage, Si adatoms as well as Br atoms desorb remarkably. The cross section of Br atom desorption first increases near 15 eV and then increases by orders of magnitude with an electron energy up to 150 eV. The cross section of adatom desorption, in contrast, is much less dependent on the electron energy in the above energy region. The desorption behavior is discussed in terms of electronic excitation at the Br-chemisorbed Si(111) surface.