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Quantitative surface analysis includes the determination of the elemental composition and the structure of the sample under investigation. Although LEED, XPS, and SPM etc. have been used to investigate the surface structure of the materials, ambiguity remains in determining quantitatively the topmost atomic species and its alignment on an atomic scale. Therefore, we adopted coaxial impact collision ion scattering spectroscopy (CAICISS) to identify the terminating structure of compound materials such as SrTiO 3 (001), InP(001) etc. As a result of the measurements, we could determine the topmost atomic plane of those materials. CAICISS is considered to be a powerful tool for those topmost surface analysis of the materials.

We have synthesized a Monte Carlo program to simulate the time-of-flight (TOF) spectra of coaxial impact collision ion scattering spectroscopy (CAICISS). This program is based on the binary collision model considering inelastic energy loss and follows the incoming and outgoing trajectories for each incident ion from a top surface up to 300 monolayers (MLs) below a surface. The present simulation reproduced well the observed overall TOF spectra from MoS 2 (0001), whose surface structure was already known. It was also found that the ions backscattered from the atoms located in the depths from top surface down to 150th atom layer contributed to the TOF spectrum. In order to extract quantitative information on surface structures from CAICISS spectra, it is essential to estimate accurately the background originated from the backscattering at the depths. The CAICISS measurement followed by the Monte Carlo simulation was applied to structure analysis of a TiO 2 -terminated SrTiO 3 (001) surface prepared by a chemical treatment and confirmed that the topmost layer comprised a TiO 2 layer and the SrO fraction was estimated to be less than 5%.

The topmost atom of InP (001) surfaces, which were annealed at temperatures between 300 and 550°C or sputtered with 1 keV Ar+ at 300°C in ultra high vacuum, has been directly identified by means of coaxial impact collision ion scattering spectroscopy (CAICISS). Time-of-flight spectra of the annealed InP (001) surface exhibited both In and P peaks in both\([\overline {\text{1}} {\text{ }}10]\) azimuth and in [100] azimuth, which revealed that the topmost layer of annealed InP (001) was comprised of In-terminated and P-terminated surfaces. On the other hand, time-of-flight spectrum of the InP (001) sputtered at 300°C revealed only an In peak in\([\overline {\text{1}} {\text{ }}10]\) azimuth and revealed both In and P peaks in [100] azimuth. This result indicates that the topmost layer on the Ar+-sputtered InP (001) surface was completely terminated by In atoms. Furthermore, we indicate that surface damage induced by this sputtering treatment is little. The azimuthal depen-dence of CAICISS intensity scattered from In and P showed twofold symmetry with respect to [100] direction, which originated from the zinc-blende structure.

The terminating structure of 6H-SiC (0001) fabricated by the Acheson method was directly identified by means of Coaxial Impact Collision Ion Scattering Spectroscopy (CAICISS). The CAICISS spectra proved that the topmost surfaces of samples were Si-terminated planes for both the front and the rear faces. Furthermore, according to the azimuthal dependence of Si peak in TOF spectra, it was also proved that the (0001) Si face was composed of the Si-terminated flat terraces and steps whose height is 7.56 A corresponding to a half unit cell length of the c-axis of 6H-SiC.

The hetero- and homoepitaxial deposition of GaAs films by the ionized cluster beam technique in connection with subsequent neutral beam deposition forming a double layer structure have been studied. It is found that ICB-deposited films have superior quality in comparison with conventional ion beam deposited films and comparable quality like MBE or MOCVD-deposited films. By the fabrication of device structures, it has been proved that the start of film growth from an interface formed by an ICB-deposited As layer is advantageous. Additionally, surface cleaning by low-energy ionized cluster beams has been studied. For the first time, defect-free surface cleaning by low-energy cluster ion beams has been realized.

It has been found that the exposure of a Si (100) surface to an As ionized cluster beam (ICB) is effective in the preparation of the surface prior to epitaxial growth of GaAs under conventional high vacuum conditions of 2×10−5 Pa. This process is achieved at a temperature as low as 600 °C. A clear 1×2 or 2×2 reflection high energy electron diffraction pattern observed after the procedure indicates good ordering of the sample surface. The cleaning process is attributed to chemical and physical sputtering by As ICB in the first stage and to the subsequent As termination of Si dangling bonds. It has been found that the optimum preparation conditions are an accelerating voltage of the As ionized cluster beam of 1.3 kV and a substrate temperature of 600 °C. GaAs films deposited on As ICB treated Si (100) substrates show good crystal quality with single domain structure.

The terminating structure of 6H–SiC(0001) substrates fabricated by the Acheson method was directly identified by means of coaxial impact collision ion scattering spectroscopy (CAICISS). The CAICISS spectra showed that the topmost surfaces of the samples were Si-terminated planes for both the front and rear faces. It was also shown that the (0001)Si face was composed of Si-terminated flat terraces and steps, the height of which corresponded to one-half the unit cell length along the 6H–SiC c axis.

The terminating atomic plane of SrTiO3 (001) surface was investigated by means of coaxial impact‐collision ion scattering spectroscopy (CAICISS). CAICISS spectra proved that SrTiO3 (001) surfaces of as‐supplied substrates as well as of O2‐annealed substrates were predominantly terminated with TiO2 atomic plane, while the SrO atomic plane came at the topmost surface of SrTiO3 (001) homoepitaxial film. This indicates the structural conversion of the topmost atomic layer from TiO2 to SrO occurred during the SrTiO3 homoepitaxial growth. The azimuth rotational CAICISS spectra exhibited a fourfold symmetry in the surface atom alignments, showing the square lattice structure of a terminating plane.

The topmost atoms of TiO2 - terminated SrTiO3(001) annealed at temperatures between room temperature and 800°C in ultra high vacuum (UHV), have been studied by means of in-situ coaxial impact collision ion scattering spectroscopy (CAICISS). Both time-of-flight spectra at the incident angle of 45.0°C along [ $$\overline{1}$$ 00] azimuth and of 35.3°C along [ $$\overline{1}\overline{1}$$ 0] azimuth revealed Ti and weak O peaks and no Sr peak at 150°C, which means that the topmost layer at 150°C is terminated by TiCh-plane, completely. On the other hand, as increasing the substrate temperature, Sr peak began to appear above 400°C. This Sr peak intensity from both directions was drastically increased with elevating the substrate temperature. This indicates that the topmost O and Ti atoms desorb from the surface at the higher substrate temperature. The ratio Sr/Ti corresponds to the amount of the topmost oxygen or titanium vacancies due to the desorption. It was found that 40 % of the topmost oxygen atoms and 32% of the topmost titanium atoms desorb from TiO2-terminated SrTiO3(001) surface at 800°C. The activation energies for oxygen and titanium desorption were 0.28eV and 0.40eV, respectively.

In situ characterization of the topmost surface of SrTiO3(001) was performed by means of coaxial impact collision ion scattering spectroscopy. As a result, it was proven that the displacement of Sr atoms occurred in the surface region at high temperatures around 500 °C in the case of the as-supplied SrTiO3 substrates terminated with TiO2 atomic plane. Sr atoms shifted by 0.012±0.002 nm toward [001] direction. On the other hand, no displacement was observed in the case of O2 annealed samples at 1000 °C for 10 hours. It indicated that the stable topmost surface structure was formed by the high temperature annealing in the SrTiO3 substrates.

Molecular layer epitaxy and the topmost surface structure in laser MBE of perovskite and other related oxides were investigated by in situ RHEED, in situ angle-resolved XPS (ARXPS) and ex situ co-axial ISS (CAICISS) analyses. Two-dimensional epitaxial growths of SrTiO3 (001) and BaCuO2(001) on SrTiO3(001) substrate were achieved by optimizing the growth conditions. Periodicities of RHEED oscillation corresponded well to the growth of a repeating unit cell (molecular layer). ARXPS and CAICISS spectra revealed that (Sr-0) atomic plane came at the top of SrTiO3(001) film growing on SrTiO3 (001) substrate with (Ti-O) atomic plane on the top. This indicates the structural conversion of the topmost atomic layer from TiO2 to SrO occurred during the SrTiO3 homoepitaxial growth.

Polycrystalline samples La2−x Ba x CuO4+δ(0 ≤ x ≤ 0.145), being prepared by the conventional solid state technique, were electrochemically oxidized at room temperature, and their lattice parameters, electrical resistivities, magnetic susceptibilities, Seebeck coefficients, and gas evolution with increasing temperature were measured. All the electrolyzed samples showed a Tc ≥ 31 K, except for x = 0.125, and possessed almost constant hole concentration p ≈ 0.16 holes/formula unit. The result of TG-Mass-spectrometry showed that the oxidation of copper ions can not be attributed only to the incorporation of excess O2- ions into the lattice.

Room-temperature (20° C) epitaxy of high-melting point CeO2 thin films was achieved for the first time on Si(111) substrates. Cross-sectional high-resolution transmission electron microscopy, Rutherford backscattering spectrometry and ion scattering spectroscopy confirmed the formation of a sharp oxide/silicon heterointerface with no boundary amorphous layer and single crystallinity of the present CeO2 films. This was achieved by pulsed laser deposition in an ultrahigh vacuum under optimized oxygen partial pressures and by hydrogen termination of the Si surface.

The reason why electrical characteristics of GaAs films grown on CaF2/Si(111) structures at high substrate temperature (600°C) are degraded is studied. Rutherford backscattering spectroscopy (RBS) measurements and secondary ion mass spectroscopy (SIMS) observations revealed that the degradation was due to point defects which resulted from a degraded interface region formed by mutual diffusion between GaAs and CaF2. It was found that the 2-step growth method was effective in reducing the point defects of GaAs film.