Regensburg 2007 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 21: III-V semiconductors II
HL 21.4: Vortrag
Dienstag, 27. März 2007, 11:45–12:00, H17
Formation of MOVPE grown InAs quantum dots on GaAs(001):Si investigated with in-situ STM — •Raimund Kremzow1, Markus Pristovsek1, Bert Rähmer1, Markus Breusing1, Michael Kneissl1, and Wolfgang Richter2 — 1TU-Berlin, Institut für Festkörperphysik, Sekr. PN6-1, Hardenbergstraße 36, 10623 Berlin, Germany — 2Dipartimento di Fisica, Roma II (Tor Vergata), Via della Ricerca Scientifica 1, 00133 Rome, Italy
Metal-Organic Vapour Phase Epitaxy (MOVPE) is the most important growth method for III-V-semiconductor structures. However, in-situ measurement techniques during MOVPE are constrained by the typical pressures of 20-100 mbar and temperatures of 450°C - 1100°C to optical techniques, which do not reveal microscopic details. Therefore, we have designed and built the first in-situ scanning tunnelling microscope (STM) capable of measuring the topography of semiconductor surfaces continuously during the growth of nanostructures in MOVPE up to 700°C. We will present our latest results, e.g. the first measurements of Ostwald-ripening of InAs quantum dots on a GaAs(001) surface. After the growth of InAs quantum dots a sequence of in-situ STM images were recorded at a sample temperature of 475°C. Three different structures (quantum dots, small and big clusters) could be differentiated. During the Ostwald-ripening the density of the small clusters seems to be constant, while the small quantum dots vanished exponentially and the big clusters increased slightly.
This newly developed in-situ STM tool could also enable effective control of semiconductor nanostructures during MOVPE growth.