Shiro　Tsukamoto

Greeting

High density arrays of Quantum dots (QDs) can easily be grown by 'self-assembled' methods. These QDs are strong candidates for advanced semiconductor quantum devices. However, the precise mechanism of 'self-assembled' is not understood, which hampers control over QD size, density and distribution for particular applications. Therefore, in situ evaluation technique for observing the growth process is necessary and indispensable. The techniques, RHEED and RDS, which use the electron beam or light, respectively, has already been put to practical use, and these are used widely now. However, even though the atomic level control for Layer by layer growth is enabled, the three dimensions growth cannot be evaluated at atomic-level and real-space by these techniques. Here, STM is good technique to observe the surface in atomic level but it dislikes vibrations and material depositions. So, usually its observation is after transporting the sample from MBE growth chamber to the STM though a gate valve, resulting that the temperature of the sample is returned to room temperature. Since the real in situ observation cannot be done with this ordinary method, we develop "STMBE" system in which the STM is placed completely inside MBE growth chamber, and with this system, the surface structure is analyzed centering on the in situ STM observation of the InAs QD self-assemble process on GaAs(001). Moreover, in order to improve the catalyst revitalization, we are doing the research of fixing organometallic catalyst on the semiconductor surface.

Research Activity Log (until Jan.7, 2010)
Shiro Tsukamoto.pdf(438)