Regensburg 2010 – scientific programme
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O: Fachverband Oberflächenphysik
O 68: Semiconductor substrates: Epitaxy and growth
O 68.9: Talk
Thursday, March 25, 2010, 12:30–12:45, H42
Evolution of the surface reconstructions during the growth of an InAs wetting layer on GaAs(001)-c(4×4) — •Holger Eisele, Jan Grabowski, Christopher Prohl, Britta Hoepfner, and Mario Daehne — Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin
We studied the growth of the first monolayer of InAs on the GaAs(001)-c(4×4) surface using a combined UHV-MBE-(RHEED)-STM setup, which provides atomically resolved images of the growth surfaces. For a coverage below about 2/3 of an monolayer of deposited InAs we observe single signatures of the deposited material at the GaAs(001)-c(4×4) surface. The number of these signatures is proportional to the amount of deposited InAs. They occur first at the domain boundaries and further at the hollow sites of the GaAs(001)-c(4×4) reconstruction. At a coverage of about 2/3 of a monolayer an abrupt phase transition occurs in the RHEED. Also the STM images changes completely from the c(4×4) reconstruction to a flat topmost layer, showing an (n×3) periodicity along [110] direction. The detailed analysis of this layer exhibits an in-line (4×3) reconstruction alternating with a brick-lined c(4×6) reconstruction, shifted to each other along the [-110] direction by the insertion of an (6×3) surface unit cell. The stoichiometry of the (4×3) could be determined to In2/3Ga1/3As for the topmost layer and the complete structural model for this surface reconstruction can be given, due to comparison of the STM images with DFT-calculations. On top of this layer, the InAs grows in pure stoichiometry and forms chains and 2D islands with α2(2×4) and β2(2×4) reconstructions.