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O: Oberflächenphysik

O 25: Epitaxie und Wachstum II

O 25.4: Vortrag

Dienstag, 9. März 2004, 16:30–16:45, H39

Bare surface structures and quantum dots growth on the GaAs(315)B surface — •Takayuki Suzuki, Yevgeniy Temko, Mingchun Xu, and Karl Jacobi — Fritz-Haber-Institut der Max-Planch-Gesellshaft, Faradayweg 4-6, 14195 Berlin

Surface structures of the GaAs(315)B surface were investigated under Ga- and As-rich conditions. The Ga-rich surface is not flat on atomic scale, but exhibits a very anisotropic surface morphology. Narrow stripes of 1×1 structure extend along [12-1]. The steps between the stripes often bunch together thus creating {101} facets. The As-rich surface is also not flat, but facets into vicinal (5 2 11)B surfaces with steps along the [13-1]proj. and [-321]proj.. {101} facets form on the sidewall of the steps along the [13-1]proj.. The GaAs(315)B surface becomes flat by adsorbing InAs with molecular beam epitaxy, and exhibits a c(2×2) reconstruction. Further adsorption induces quantum dots (QDs) formation. The QDs shape is given by {101}, {111}, and {2 5 11}A bounding facets. The size distribution of the QDs is quite broad, with the length at the foot ranging from 15 to 80 nm. Many QDs exhibit signs of coalescence. Stacking-faults and screw dislocations penetrating the QDs are directly detected with atomic resolution. Correlation between broad size distribution and incorporation of lattice defects are demonstrated experimentally for the first time.