STM study of copper growth on ZnO(0001)-Zn and ZnO(000-1)-O surfaces

L. V. Koplitz, O. Dulub, U. Diebold

Department of Chemistry, Loyola University, New Orleans, Louisiana 70118, U.S.A
Department of Physics, Tulane UniVersity, New Orleans, Louisiana 70118, U.S.A

J. Phys. Chem. B 107 (2003) 10583-10590

The room-temperature growth of Cu on the polar (0001)-Zn and (000-1)-O surfaces of zinc oxide has been studied with scanning tunneling microscopy (STM). Copper grows on the (0001)-Zn surface as three-dimensional clusters even at low coverages (0.05-0.25 monolayers (ML)); two-dimensional (2D) islands are only observed at very low coverages (0.001-0.05 ML). The average size of the 3D clusters increases with coverage, and their density increases slowly. Surface roughness and sputter damage change the growth mode to more 2D-like. The Cu clusters are well-separated and exhibit a well-defined hexagonal shape. Equilibrium crystal shape analysis yields an apparent work of adhesion of 3.4 +- 0.1 J/m2 for the largest clusters. On the (000-1)-O surface, formation of two-dimensional Cu clusters was observed at coverages of less than 0.1 ML.

Corresponding author: Ulrike Diebold (diebold at iap_tuwien_ac_at).

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