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O: Oberflächenphysik

O 20: Halbleiteroberfl
ächen und -grenzfl
ächen

O 20.1: Talk

Tuesday, March 25, 2003, 15:00–15:15, FOE/ANOR

Determination of adatom diffusion barriers on InP(110) surfaces from desorption experiments — •Philipp Ebert, Ulrich Semmler und Knut Urban — Institut für Festkörperforschung, Forschungszentrum Jülich, D-52425 Jülich, Germany

We present in-situ variable temperature scanning tunneling microscopy measurements of the phosphorus vacancy formation on cleaved p-doped InP(110) surfaces. The vacancy concentrations and the formation rates are found to increase with temperature. An Arrhenius analysis of the data reveals a barrier of (0.47 ± 0.05) eV and a pre-exponential factor of (1.6 ± 0.7) Hz for the vacancy formation. The very unusual pre-exponential factor can be explained on basis of rate equations describing the desorption of phosphorus from the surface in form of P_2 molecules. It will be shown that the rate limiting process for the vacancy formation is the P adatom diffusion and that the activation energy for diffusion is given by the barrier for vacancy formation of (0.47 ± 0.05) eV. Furthermore, the measurements show that P adatom diffusion is highly anisotropic, leading to an essentially one-dimensional diffusion.