Yoshiaki Aiso

Lattice Matching of α-Cyclodextrin Commensurate with Molybdenum Disulfide Studied by Scanning Tunneling Microscopy

Lattice matching between α- cyclodextrin (α- CyD) and molybdenum disulfide ( MoS2) was investigated by scanning tunneling microscopy (STM) using the CyD molecular necklace and molecular tube as specimens. Stable sites for α- CyD on the MoS2 substrate observed by STM were in good agreement with the model we proposed.

Selenium-treated GaAs(001)-2×3 surface studied by scanning tunneling microscopy

An Se‐passivated GaAs(001) surface was found to be stabilized by 2×3 reconstruction, previously reported as an intermediate structure, under the condition of a low Se chemical potential. Ordered elliptical protrusions with ∼0.6‐nm periodicity in the [110] direction were observed by scanning tunneling microscopy, the structure of which was in good agreement with a double‐layered dimer model. A comprehensive model to explain the 2×3 structure together with the formation of a Ga2Se3‐like structure with ordered 1/3 ML Ga vacancies was proposed.

Surface structures of Gaas passivated by chalcogen atoms

Abstract When a GaAs(001) surface with Se adsorbates was flash-heated under a low chemical potential condition, a 2 × 3 RHEED pattern, previously reported as an intermediate structure, remained even after the sample was cooled. The atomic structure observed by STM is in good agreement with the dimer model proposed to explain the chalcogen-passivated GaAs(001) surfaces. Se dimers were found to be buckled, but the 2 × -periodicity was maintained in the [ 1 10] direction, unlike the previously observed 4 × -structure forming the dimer row pairs. Some other structures, the axes of which are in directions different from [110], were also observed on the Se/GaAs(001) surface. The S-passivation effect was studied by measuring current-voltage properties for the S/GaAs(001) surface.

Surface Structures of GaAs(001) with Selenium Adsorbate Studied by Scanning Tunneling Microscopy

Under the low chemical potential condition, new structures other than the 2×1 and 2×3 structures were found on the Se-treated GaAs(001) surface. These structures consist of elliptical protrusions with 0.6 nm periodicity in the [110] direction, similarly to the STM images obtained for the 2×3 surface. Their axes, however, are in directions different from [110].

Dimer Model for Comprehensive Interpretation of Selenium-Passivated GaAs(001) Surface Structures

A mechanism to explain Ga2Se3-like structural formation on a selenium treated GaAs(001) surface was proposed through the analysis of the selenium-treated GaAs(001)-2×3 surface by scanning tunneling microscopy, where ordered 1/3 ML Ga vacancies in the second layer and replacement of As atoms in the third layer can be introduced through the phase transition between 2×1 and 2×3 structures upon heat treatment.