Berlin 2005 – wissenschaftliches Programm

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O: Oberflächenphysik

O 49: Epitaxie und Wachstum II

O 49.1: Vortrag

Dienstag, 8. März 2005, 15:45–16:00, TU EB407

In-situ STM Measurements during MOVPE — •M. Breusing, B. Rähmer, M. Pristovsek, R. Kremzow, and W. Richter — TU-Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, 10623 Berlin

Although numerous ex-situ and in-situ studies on nanostructures have been done the effects taking place on the surface during epitaxy are not completely understood. Most severe is the lack of in-situ tools for the Metal-Organic Vapour Phase Epitaxy (MOVPE) providing more information about the sample’s topography then mean roughness.

Scanning Tunneling Microscopy (STM) is a technique which would directly give quantitative information about the topography and could work under a typical MOVPE reactor pressure of 100 mbar. However, an in-situ STM in a MOVPE growth environment has not been realized so far, because of many unsolved problems.

Indeed, the development of a STM for in-situ MOVPE measurements requires a completely new set-up. The limited space in the MOVPE reactor and the high temperatures during growth near the susceptor, caused by the thermal conductivity of the carrier gas, require a special design of the STM. On the other hand the influence of the STM on the growth (flow pattern in the reactor) must be minimized.

For these conditions we developed an in-situ STM which can resist sample-temperatures up to 550^∘C continuously. We were able to make the first STM measurements during InAs MOVPE growth on a GaAs stebpunching surface, showing resolution better than 4 nm vertically and 20 nm laterally.