METHOD FOR INDEPENDENT CONTROL OF PARTICLE-SIZE AND DISTANCE IN RHODIUM EPITAXY ON TIO2(110)-(1 X-2) SURFACE - AN STM STUDY

A method for independent control of the particle size and distance is presented for rhodium epitaxy on TiO2(110)-(1 x 2) surface. The real s pace imaging of the surface morphology was performed bq scanning tunne ling microscopy. The amount of the deposited rhodium was checked by Au ger electron spectrometry. The method consists of two steps: (i) evapo ration of 0.001-0.050 ML equivalent of rhodium at room temperature wit h a post-annealing at 1100 K (''seeding''); (ii) post-deposition of rh odium for growing of the Rh nanoparticles formed in step (i) (''growin g''). The mechanism of this procedure is based on the large difference of the surface diffusion coefficient between Rh adatoms and Rh nanocr ystallites larger than 1-2 nm. In the first step the average distance between the metal particles is controlled in the range 5-200 nm, the s econd step determines the particles size (2-50 nm). This work demonstr ates that the diffusion processes of metal nanoparticles of different sizes and the growing modes of the crystallites can be studied in dera il by application of seeded surfaces. (C) 1998 Elsevier Science B.V.