AVS 50th International Symposium
    Semiconductors Thursday Sessions
       Session SC-ThM

Paper SC-ThM6
Heteroepitaxy of III-Se Materials: Compatibility to Si and Their Growth Studied by In-situ Scanning Probe Microscopy

Thursday, November 6, 2003, 10:00 am, Room 326

Session: Heteroepitaxy and Strain Engineering
Presenter: T. Ohta, University of Washington
Authors: T. Ohta, University of Washington
A. Klust, University of Washington
J.A. Adams, University of Washington
Q. Yu, University of Washington
M.A. Olmstead, University of Washington
F.S. Ohuchi, University of Washington
Correspondent: Click to Email
Heteroepitaxy of semiconductors on silicon is essential for expanding Si-based technology beyond standard microelectronics. Materials consisting of Group III (Ga and Al) and selenium (Se) are of particular interest, combining Si compatibility with structural versatility and optical band gaps (Eg(Ga@sub x@Se@sub y@)=1.8-2.6eV and Eg(Al@sub x@Se@sub y@)>3.1eV). We present a study of heteroepitaxy of layered GaSe on Si(111) using scanning tunneling microscopy (STM). GaSe is composed of a stack of iono-covalently bonded quad layers (QL) of Se-Ga-Ga-Se with van der Waals interactions between the layers. Of general interest for the growth of layered materials whether the full QL is required for layer nucleation. During growth, we observed: (1) formation of a pseudomorphic GaSe-bilayer, (2) development of triangular QL nuclei, followed by (3) layer-by-layer growth of GaSe layers. The first GaSe bilayer perfectly passivates the Si(111), making its surface environmentally inert. Triangular islands, one QL thick, nucleate on this passive surface with their edges aligned to <11-2> of Si(111). Nuclei with two orientations, rotated by 180°, are observed, leading to orientational domains in thicker layers. We characterized their electronic structures and the type of defects incorporated in the domains. In thicker films, GaSe layers often extended over substrate atomic steps, showing a "carpet-on-steps" morphology. This work is supported by NSF Grant DMR 0102427 and the M. J. Murdock Charitable Trust. T. O. further acknowledges support by UIF Nanotechnology fellowship of the University of Washington, and A. K., the Alexander von Humboldt-Foundation, Germany.