Hiroyoshi Soejima

Coaxial impact-collision ion scattering spectroscopy (CAICISS): A novel method for surface structure analysis

Abstract A novel low-energy ion scattering spectrometer, in which an ion source and an energy analyzer are arranged coaxially so that the experimental scattering angle is just 180°, has been constructed. This mode of low-energy ion scattering spectroscopy, which we call coaxial impact-collision ion scattering spectroscopy (CAICISS), has several advantages. For example, CAICISS is suitable for in situ observation of various surface processes (e.g., epitaxial film growth at semiconductor surfaces) because of its geometrical simplicity. Preliminary experiments using the CAICISS apparatus have been made for a Au/Si(111) surface.

Real-time monitoring of molecular-beam epitaxy processes with coaxial impact-collision ion scattering spectroscopy (CAICISS)

Abstract Coaxial impact-collision ion scattering spectroscopy (CAICISS) is a novel form of low-energy ion scattering spectroscopy (ISS), in which a pulsed-beam low-energy ion source and a time-of-flight ion energy analyzer are placed coaxially so as to cover the experimental scattering angle at 180°. It is demonstrated that CAICISS is useful for monitoring molecular-beam epitaxy (MBE) processes in real time by taking the MBE growth of AlAs on a GaAs(001) substrate as an example.

Development of Scanning µ-RHEED Microscopy for Imaging Polycrystal Grain Structure in LSI

A new type of scanning µ-RHEED (reflection high energy electron diffraction) microscope has been developed. Three diffraction spots of a RHEED pattern were simultaneously selected for imaging. The scanning µ-RHEED images were obtained from the intensity change of the diffraction spots. The distribution of normally rotated micrograins inside the same planes grain parallel to the surface was successfully observed from the scanning µ-RHEED images. Micrograin structures of poly-Si and Cu thin films were observed with a resolution of less than one micron.

New Display‐type Analyzer for Three‐dimensional Fermi Surface Mapping and Atomic Orbital Analysis

We have developed and installed a new Display‐type ANAlyzer (DIANA) at Ritsumeikan SR center BL‐7. We measured the angle‐integrated energy distribution curve of poly‐crystal gold and the photoelectron intensity angular distribution (PIAD) of HOPG to estimate the total energy resolution and to check the condition of the analyzer. The total energy resolution (ΔE/E) is up to 0.78%, which is much higher than the old type. The PIAD of HOPG we obtained was the ring pattern as expected. Therefore, a detailed three‐dimensional Fermi surface mapping and an analysis of the atomic orbitals constituting the electron energy bands are possible by combining them with a linearly polarized synchrotron radiation.