Yujin Yamazaki

Structural Analysis of 6H–SiC(0001)√3×√3 Reconstructed Surface

Using coaxial impact-collision ion scattering spectroscopy (CAICISS), the structure of the 6H–SiC(0001)√3×√3 reconstructed surface was investigated. As a result of composition analysis, the topmost layer of this surface was found to be covered with Si adatoms. Moreover, from the incidence angle dependence of the scattering intensity due to C atoms, it was found that the √3×√3 periodicity was formed by a one-third monolayer of Si adatoms occupying T4 sites, and the height of the Si adatoms from the first substrate layer was determined to be 1.5±0.2 A.

Influence of Hydrogen-Surfactant Coverage on Ge/Si(001) Heteroepitaxy

The growth of Ge on Si(001) at 300°C with dynamically supplied atomic hydrogen (H) as a surfactant has been monitored in real time using coaxial impact-collision ion scattering spectroscopy and time-of-flight elastic recoil detection analysis feasible in a gas phase atmosphere. It has been revealed that (1) a submonolayer of H atoms readily acts as a surfactant, (2) the intermixing of Ge and Si occurs at the initial stage of Ge growth in the presence of H-surfactant, and (3) beyond optimal H coverage of about 0.6 monolayer, the roughening of Ge films occurs even though a monohydride phase is maintained at the growth front.

Coaxial Impact-Collision Ion Scattering Spectroscopy and Time-of-Flight Elastic Recoil Detection Analysis for In Situ Monitoring of Surface Processes in Gas Phase Atmosphere

Based on conventional coaxial impact-collision ion scattering spectroscopy (CAICISS) and time-of-flight elastic recoil detection analysis (TOF-ERDA), we have developed a novel ion scattering and recoiling spectrometer equipped with a differential pumping system for in situ monitoring of surface processes in gas phase atmosphere in the pressure regime up to 10-4 Torr. In order to demonstrate the performance of this apparatus, we have applied it to real-time monitoring of Ge thin film growth on a Si(001) surface in atomic hydrogen (H) atmosphere. The morphology of Ge thin films and H coverage on the growth front during the growth in H atmosphere were successfully observed.

Ge thin film growth on Si(111) surface using hydrogen surfactant

Abstract We have investigated the atomic hydrogen (H)-surfactant mediated growth of Ge on Si(111) surface, using coaxial impact-collision ion scattering spectroscopy (CAICISS), time-of-flight elastic recoil detection analysis (TOF-ERDA) and scanning electron microscopy (SEM). It has been found that the Ge thin film on the Si(111)1×1-H surface is flattened by the H-surfactant, whilst on the Si(111)7×7 surface the flatness does not change in spite of supplying H. These results indicate that the flatness of the Ge thin film is strongly influenced by the structure of the Si(111) substrate surface at the initial stage of Ge thin film growth.

Adsorption of Atomic Hydrogen on Ag-Covered 6H-SiC(0001) Surface

We have investigated atomic hydrogen (H) adsorption on an Ag-covered 6H-SiC(0001) surface, using coaxial impact-collision ion-scattering spectroscopy (CAICISS) and time-of-flight elastic recoil detection analysis (TOF-ERDA). It has been revealed that the two-dimensional (2D) layer of Ag on the 6H-SiC(0001) surface is changed to three-dimensional (3D) islands by the adsorption of H on the surface. The 3D Ag islands have an Ag(111) crystalline structure. When this surface is annealed at 550°C, the 3D Ag islands do not revert to a 2D layer but desorb from the surface together with H.