Scanning tunneling microscopy studies of the growth of Cu clusters on a reconstructed TiO2(110)-(1 x 2) surface

Copper clusters grown on a reconstructed TiO2 (110) surface were studied by scanning tunneling microscopy (STM). The titania surface exhibited low ene rgy diffraction patterns corresponding to the (1 x 2) reconstruction, but S TM studies revealed that this surface was not fully reconstructed. Specific ally, gaps in the characteristic (I x 2) atomic row structure were observed , illustrating that this partially reconstructed surface is much more defec tive than the (I x 1) surface. Copper clusters grown on the reconstructed T iO2 (110) surface showed the same basic self-limiting growth characteristic s as Cu on TiO2(110) - (1 x 1). For coverages between 0 - 0.5 ML, a fairly narrow size distribution was observed, and the island densities rather than cluster sizes increased with coverage. Annealing to 700 K resulted in incr eased cluster sizes, but the narrow size distribution was maintained. The m ain difference between growth on the (I x 1) vs. reconstructed surface was in the cluster sizes, densities and spatial distributions. On the reconstru cted surface, the cluster sizes were smaller while cluster densities were m uch higher (6.2 x 10(12) vs. 3.0 x 10(12) at 0.5 ML), and even the annealed Cu clusters displayed no preference for residing at the step edges, These characteristics are attributed to reduced mobility of the Cu atoms on the h ighly defective, reconstructed surface. (C) 2001 Elsevier Science B.V. All rights reserved.