Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 27: Surface Dynamics: Theory
O 27.7: Vortrag
Dienstag, 21. März 2017, 12:15–12:30, TRE Phy
Theoretical description of Ge(001) surface reconstruction — •Katharina Noatschk1,2, Wolfgang Klesse2, Thomas Schroeder1,2, and Götz Seibold1 — 1Brandenburg Technical University Cottbus-Senftenberg, 03046 Cottbus, Germany — 2IHP-Innovations for High Performance Microelectronics, 15236 Frankfurt(Oder), Germany
In our work we study the reconstruction of the Ge(001) surface within the Ising model. Due to the reduced bonding of surface atoms adjacent germanium surface atoms tend to form so-called tilted dimers [1]. Experimentally one observes at low temperature the c(4x2) structure which corresponds to an alternating tilt pattern whereas at high temperature the overall tilt vanishes. In addition to the c(4x2) structure experimental and theoretical work also indicates the presence of an intermediate p(2x2) structure with alternating tilts only along one cristallographic axis whereas it is constant along the other. In our investigations we represent the two tilt directions of a dimer by an Ising spin and take the interaction parameters between Ising variables from first principle calculations [2]. We evaluate the phase diagram for the various dimer order parameters within a Metropolis algorithm. Moreover, we obtain from the Monte Carlo simulation domains on the surface which are consistent with the experimental measurements.
[1] D.J. Chadi, Phys. Rev. Lett. 43 (1979) 43
[2] Y. Yoshimoto, et al. Phys. Rev. B 61 (2000) 1965