SPring-8, the large synchrotron radiation facility

Date&Time: June 11, 2003, 16:00-17:00

Speaker: Prof. Shiro Tsukamoto
Affiliation: Institute of Industrial Science, University of Tokyo

Abstract
　　The combined molecular beam epitaxy (MBE) and scanning tunneling microscopy (STM) system has proven to be a very powerful technique for the observation of real-space semiconductor surfaces, especially GaAs(001), with extremely high lateral and vertical resolution. Recently, Avery et al. reported STM studies of submonolayer islands in the precoalescence regime grown by MBE on the three low-index surface of GaAs. However, the growth dynamics of the step edges of these surfaces are still poorly understood at the atomistic level. Since, using this combined system, samples need to be cooled and transferred to a cleaner environment for STM analysis, the step edges, especially B-step edges which provide the most active sites on GaAs(001), are evolved and no longer representative of the true growth dynamics.
　　Moreover, electron high-energy difraction (RHEED) is well known as a real-time in situ surface observation technique for the MBE growth.
　　However, the RHEED patterns shÇåow not realspace but reciprocal lattice images of surface reconstructions.
These patterns are good for the 2D, layer by layer growth, however in the 3D cases, dots growth etc., there are many missing information, especially that of atomic-level 3D structures. Therefore, we study atomic-level in situ realspace observations on the MBE growth front with a system in which STM and MBE can be performed simultaneously.